PROGENITOR INC
S-1/A, 1996-07-11
BIOLOGICAL PRODUCTS, (NO DIAGNOSTIC SUBSTANCES)
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<PAGE>
   
     AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JULY 11, 1996
    
   
                                                      REGISTRATION NO. 333-05369
    
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
 
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
 
                            ------------------------
 
   
                                AMENDMENT NO. 1
                                       TO
                                    FORM S-1
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
    
                            ------------------------
 
                                PROGENITOR, INC.
 
             (Exact name of Registrant as specified in its charter)
 
<TABLE>
<S>                             <C>                         <C>
           DELAWARE                        2836                     31-1344193
 (State or other jurisdiction       (Primary Standard            (I.R.S. Employer
     of incorporation or                Industrial            Identification Number)
        organization)              Classification Code
                                         Number)
</TABLE>
 
                               1507 CHAMBERS ROAD
                              COLUMBUS, OHIO 43212
                                 (614) 488-6688
               (Address, including zip code and telephone number,
       including area code, of Registrant's principal executive offices)
                            ------------------------
 
                         DOUGLASS B. GIVEN, M.D., PH.D.
                     PRESIDENT AND CHIEF EXECUTIVE OFFICER
                                PROGENITOR, INC.
                               1507 CHAMBERS ROAD
                              COLUMBUS, OHIO 43212
                                 (614) 488-6688
 (Name, address, including zip code, and telephone number, including area code,
                             of agent for service)
 
                            ------------------------
 
                                   COPIES TO:
 
   
<TABLE>
<S>                                            <C>
            GAVIN B. GROVER, ESQ.                      CHARLES W. MULANEY, JR., ESQ.
          KRISTIAN E. WIGGERT, ESQ.                        SKADDEN, ARPS, SLATE,
             EDA S.L. TAN, ESQ.                               MEAGHER & FLOM
           MORRISON & FOERSTER LLP                         333 WEST WACKER DRIVE
            345 CALIFORNIA STREET                         CHICAGO, ILLINOIS 60606
       SAN FRANCISCO, CALIFORNIA 94104                        (312) 407-0700
               (415) 677-7000
</TABLE>
    
 
                            ------------------------
 
        APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC:
   As soon as practicable after the Registration Statement becomes effective.
 
                            ------------------------
 
    If  any of the securities being registered on this Form are to be offered on
a delayed or continuous basis pursuant to  Rule 415 under the Securities Act  of
1933, please check the following box./ /
 
    If  this Form  is filed  to register  additional securities  for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and list  the  Securities  Act  registration statement  number  of  the  earlier
effective registration statement for the same offering./ /
 
    If  this Form  is a post-effective  amendment filed pursuant  to Rule 462(c)
under the Securities Act, please check the following box and list the Securities
Act registration statement number of the earlier registration statement for  the
same offering./ /
 
    If  delivery of the Prospectus is expected  to be made pursuant to Rule 434,
please check the following box./ /
                            ------------------------
 
   
    THE REGISTRANT HEREBY  AMENDS THIS  REGISTRATION STATEMENT ON  SUCH DATE  OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL
FILE  A  FURTHER  AMENDMENT  THAT  SPECIFICALLY  STATES  THAT  THIS REGISTRATION
STATEMENT SHALL THEREAFTER BECOME EFFECTIVE  IN ACCORDANCE WITH SECTION 8(a)  OF
THE  SECURITIES ACT  OF 1933  OR UNTIL  THE REGISTRATION  STATEMENT SHALL BECOME
EFFECTIVE ON SUCH DATE AS THE COMMISSION, ACTING PURSUANT TO SAID SECTION  8(a),
MAY DETERMINE.
    
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>
                                PROGENITOR, INC.
                             CROSS-REFERENCE SHEET
                   PURSUANT TO ITEM 501(B) OF REGULATION S-K
 
<TABLE>
<CAPTION>
                      ITEMS OF FORM S-1                                       LOCATION IN PROSPECTUS
- --------------------------------------------------------------  --------------------------------------------------
<C>         <S>                                                 <C>
   Item 1.  Forepart of the Registration Statement and Outside
             Front Cover Page of Prospectus...................  Facing Page of Registration Statement; Outside
                                                                 Front Cover Page
 
   Item 2.  Inside Front and Outside Back Cover Pages of
             Prospectus.......................................  Inside Front and Outside Back Cover Pages
 
   Item 3.  Summary Information, Risk Factors, and Ratio of
             Earnings to Fixed Charges........................  Prospectus Summary; Risk Factors
 
   Item 4.  Use of Proceeds...................................  Use of Proceeds
 
   Item 5.  Determination of Offering Price...................  Outside Front Cover Page; Underwriting
 
   Item 6.  Dilution..........................................  Risk Factors; Dilution
 
   Item 7.  Selling Security Holders..........................  Not applicable
 
   Item 8.  Plan of Distribution..............................  Outside Front and Inside Front Cover Pages;
                                                                 Underwriting
 
   Item 9.  Description of Securities to be Registered........  Description of Capital Stock
 
  Item 10.  Interests of Named Experts and Counsel............  Legal Matters; Experts
 
  Item 11.  Information with Respect to the Registrant........  Outside Front and Inside Front Cover Pages;
                                                                 Prospectus Summary; Risk Factors; Dividend
                                                                 Policy; Capitalization; Selected Financial Data;
                                                                 Management's Discussion and Analysis of Financial
                                                                 Condition and Results of Operations; Business;
                                                                 Management; Certain Transactions; Principal
                                                                 Stockholders; Shares Eligible for Future Sale;
                                                                 Description of Capital Stock; Financial
                                                                 Statements
 
  Item 12.  Disclosure of Commission Position on
             Indemnification for Securities Act Liabilities...  Not applicable
</TABLE>
<PAGE>
INFORMATION   CONTAINED  HEREIN  IS  SUBJECT   TO  COMPLETION  OR  AMENDMENT.  A
REGISTRATION STATEMENT  RELATING TO  THESE SECURITIES  HAS BEEN  FILED WITH  THE
SECURITIES  AND EXCHANGE  COMMISSION. THESE SECURITIES  MAY NOT BE  SOLD NOR MAY
OFFERS TO BUY BE ACCEPTED PRIOR  TO THE TIME THE REGISTRATION STATEMENT  BECOMES
EFFECTIVE.  THIS  PROSPECTUS  SHALL  NOT  CONSTITUTE AN  OFFER  TO  SELL  OR THE
SOLICITATION OF AN OFFER TO BUY NOR SHALL THERE BE ANY SALE OF THESE  SECURITIES
IN  ANY STATE IN WHICH SUCH OFFER,  SOLICITATION OR SALE WOULD BE UNLAWFUL PRIOR
TO REGISTRATION OR QUALIFICATION UNDER THE SECURITIES LAWS OF ANY SUCH STATE.
<PAGE>
   
                   SUBJECT TO COMPLETION, DATED JULY 11, 1996
    
PROSPECTUS
 
                                2,500,000 SHARES
   
                                     [LOGO]
    
                                  COMMON STOCK
 
    All of the 2,500,000 shares of Common Stock offered hereby are being sold by
Progenitor, Inc. ("Progenitor" or the  "Company"). Prior to the Offering,  there
has  been no public market for the Common  Stock of the Company. It is currently
estimated that the  initial public  offering price  will be  between $11.00  and
$13.00  per share.  See "Underwriting"  for a  discussion of  the factors  to be
considered in determining  the initial  public offering price.  The Company  has
applied  to list the  Common Stock for  quotation on the  Nasdaq National Market
under the symbol "PGEN."
 
    THE COMMON STOCK OFFERED  HEREBY INVOLVES A HIGH  DEGREE OF RISK. SEE  "RISK
FACTORS" BEGINNING ON PAGE 5.
 
THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
    EXCHANGE  COMMISSION OR ANY  STATE SECURITIES COMMISSION  NOR HAS THE
       SECURITIES AND  EXCHANGE COMMISSION  OR ANY  STATE  SECURITIES
           COMMISSION  PASSED  UPON THE  ACCURACY OR  ADEQUACY OF
               THIS PROSPECTUS. ANY REPRESENTATION    TO  THE
                        CONTRARY IS A CRIMINAL OFFENSE.
 
<TABLE>
<CAPTION>
                                                             UNDERWRITING
                                                             DISCOUNTS AND     PROCEEDS TO
                                           PRICE TO PUBLIC  COMMISSIONS(1)     COMPANY(2)
<S>                                        <C>              <C>              <C>
  Per Share..............................         $                $                $
  Total(3)...............................         $                $                $
</TABLE>
 
(1)  The  Company  has  agreed to  indemnify  the  Underwriters  against certain
    liabilities, including  liabilities under  the Securities  Act of  1933,  as
    amended. See "Underwriting."
 
(2)  Before deducting expenses of the Offering payable by the Company, estimated
    at $850,000.
 
(3) The Company has granted the Underwriters  a 30-day option to purchase up  to
    375,000  additional shares of Common Stock  on the same terms and conditions
    set forth above, solely to cover over-allotments, if any. If such option  is
    exercised  in full,  the total Price  to Public,  Underwriting Discounts and
    Commissions and Proceeds to Company will be  $      ,  $      and  $       ,
    respectively. See "Underwriting."
 
                            ------------------------
 
    The  shares of Common Stock offered by the Underwriters are subject to prior
sale,  receipt  and  acceptance  by  them  and  subject  to  the  right  of  the
Underwriters  to  reject  any  order  in whole  or  in  part  and  certain other
conditions. It is  expected that delivery  of such  shares will be  made at  the
offices  of the agent of Vector Securities International, Inc., in New York, New
York on or about             , 1996.
 
                             ---------------------
 
Vector Securities International, Inc.
 
                                     Tucker Anthony
                                         Incorporated
 
                                                          Genesis Merchant Group
                                                             Securities
 
                        , 1996
<PAGE>
   
[A  schematic  diagram  entitled  "Genomic  Discoveries  through   Developmental
Biology"   illustrating  Progenitor's  functional   genomics  approach  for  the
development of its three  primary discovery programs. The  upper portion of  the
diagram  indicates the basis for Progenitor's  approach with arrows denoting the
interaction between  Molecular  Biology,  Developmental  Biology  and  Medically
Relevant  Function in Early Cells and Tissues. The middle portion of the diagram
depicts Progenitor's three Primary  Discovery Programs: Leptin Receptors;  DEL-1
Gene;  and BFU-e Factor. The lower portion  of the diagram depicts the Potential
Therapeutic Applications  for  each  of  Progenitor's  three  Primary  Discovery
Programs.]
    
 
    IN  CONNECTION WITH THIS OFFERING, THE UNDERWRITERS MAY OVER-ALLOT OR EFFECT
TRANSACTIONS WHICH STABILIZE OR MAINTAIN THE MARKET PRICE OF THE COMMON STOCK OF
THE COMPANY AT  A LEVEL ABOVE  THAT WHICH  MIGHT OTHERWISE PREVAIL  IN THE  OPEN
MARKET. SUCH STABILIZING, IF COMMENCED, MAY BE DISCONTINUED AT ANY TIME.
    Progenitor  and  the Progenitor  logo are  trademarks  of the  Company. This
Prospectus may contain trademarks and servicemarks of other parties.
<PAGE>
                               PROSPECTUS SUMMARY
 
   
    THE  FOLLOWING SUMMARY  IS QUALIFIED  IN ITS  ENTIRETY BY  THE MORE DETAILED
INFORMATION AND FINANCIAL  STATEMENTS AND NOTES  THERETO APPEARING ELSEWHERE  IN
THIS PROSPECTUS. THE COMMON STOCK OFFERED HEREBY INVOLVES A HIGH DEGREE OF RISK.
SEE "RISK FACTORS."
    
 
                                  THE COMPANY
 
    Progenitor  is  a  functional  genomics company  engaged  in  the discovery,
characterization and validation of novel  genes, receptors and related  proteins
as  therapeutic  leads and  targets  for the  treatment  of major  diseases. The
Company's functional genomics approach combines developmental biology  expertise
and  proprietary  technology with  gene sequencing  and other  molecular biology
techniques to accelerate the discovery process. Using its developmental  biology
approach  to  functional genomics,  the  Company has  made  several discoveries,
including the discovery of the B219  leptin receptor, for which it filed  patent
applications in September and December 1994. Leptin is believed to have roles in
blood  cell formation  ("hematopoiesis"), reproduction and  obesity. The Company
has entered  into a  collaboration with  Chiron Corporation  ("Chiron") for  the
development  and  commercialization  of  the  Company's  proprietary  T7T7  gene
delivery system, and a collaboration with Novo Nordisk A/S ("Novo Nordisk")  for
the isolation, development and commercialization of blood cell growth factors.
 
    Developmental  biology is the study of  the genetic and cellular events that
control the development of a single fertilized egg into a fully-formed,  complex
organism.  Many genes involved in the process of cell growth and differentiation
may be expressed exclusively,  or at enhanced levels,  during certain stages  of
early  development and may become  inactive in the cells  of adult organisms. By
comparing the sequential expression of genes from one stage of early development
to the next, the Company believes it can identify, isolate and sequence specific
genes, receptors and  other proteins  which play key  roles in  cell growth  and
differentiation. The Company believes that early developmental cells and tissues
are  a rich and largely unexploited source  for genes and proteins that may lead
to the development  of treatments  for diseases characterized  by aberrant  cell
growth  and differentiation, such  as cancer, blood  and immune system disorders
and degenerative diseases associated with aging.
 
   
    Progenitor possesses a number  of proprietary technologies  that it uses  in
its  discovery programs. The Company has  developed proprietary methods and cell
lines using mouse (murine) embryonic stem cells for studying the differentiation
of cells in  the early development  of tissues and  organs. Progenitor also  has
developed  proprietary  techniques to  isolate,  grow, maintain  in  culture and
differentiate cells from the murine yolk sac. The yolk sac contains the earliest
cells in development that are committed to differentiate into the blood,  immune
and  vascular systems.  In addition,  Progenitor has  developed proprietary gene
cloning and screening  techniques to  identify genes that  encode receptors  for
growth  factors believed to be important in hematopoiesis and cancer therapy, as
well as the growth and development of neural and other tissues.
    
 
    Progenitor has used its functional genomics approach to make three principal
discoveries. In addition to its B219 leptin receptor discovery, the Company  has
discovered,  in  collaboration  with Vanderbilt  University  ("Vanderbilt"), the
developmentally-regulated endothelial cell locus ("DEL-1") gene. The DEL-1  gene
is  involved in the early growth and  development of blood vessels and bone. The
Company  believes  that  DEL-1  may  have  potential  applications  in  diseases
accompanied by excessive blood vessel formation, such as cancer, and in diseases
such  as cardiovascular and other disorders that may be treatable by stimulating
blood vessel growth.  The Company  also has  identified a  murine burst  forming
units-erythroid  ("BFU-e") red  blood cell  growth factor  activity. The Company
believes that a BFU-e factor may be useful in the development of treatments  for
a variety of blood disorders.
 
    The  Company  currently  is  focusing  its  efforts  and  resources  on  the
discovery, characterization and  validation process  and intends  to enter  into
strategic alliances for the development and commercialization of drugs and other
products  based on its discoveries.  In March 1995, the  Company entered into an
agreement with Chiron for the development and commercialization of the Company's
T7T7 gene delivery system  for selected applications. In  May 1995, the  Company
entered  into a  development and  commercialization agreement  with Novo Nordisk
relating to the BFU-e red blood cell growth factor.
 
    The  Company  was   incorporated  in   Delaware  in  February   1992  as   a
majority-owned  subsidiary of Interneuron Pharmaceuticals, Inc. ("Interneuron"),
and commenced operations in May  1992. Following the Offering, Interneuron  will
own   51.2%  of  the   Company's  Common  Stock   (48.7%  if  the  Underwriters'
over-allotment option is exercised in full). The Company's executive offices are
located at 1507 Chambers Road, Columbus, Ohio 43212, and its telephone number is
(614) 488-6688.
 
                                       3
<PAGE>
                                  THE OFFERING
 
   
<TABLE>
<S>                                                   <C>
Common Stock offered................................  2,500,000 shares
Common Stock to be outstanding after the Offering...  7,293,819 shares (1)
Use of proceeds.....................................  To fund research and development activities, to
                                                      fund expansion of facilities and acquisition of
                                                      equipment, and for working capital and general
                                                      corporate purposes. See "Use of Proceeds."
Proposed Nasdaq National Market symbol..............  PGEN
</TABLE>
    
 
                             SUMMARY FINANCIAL DATA
                     (IN THOUSANDS, EXCEPT PER SHARE DATA)
 
<TABLE>
<CAPTION>
                                                                                                     SIX MONTHS ENDED
                                                                     YEARS ENDED SEPTEMBER 30,          MARCH 31,
                                                                  -------------------------------  --------------------
                                                                    1993       1994       1995       1995       1996
                                                                  ---------  ---------  ---------  ---------  ---------
<S>                                                               <C>        <C>        <C>        <C>        <C>
STATEMENT OF OPERATIONS DATA:
  Revenues......................................................  $  --      $  --      $   2,821  $       5  $     912
  Expenses:
    Research and development....................................      3,116      4,113      4,228      1,661      1,706
    General and administrative..................................      1,339      1,275      1,116        534        691
    Interest....................................................        246        648        352        304         56
                                                                  ---------  ---------  ---------  ---------  ---------
      Total expenses............................................      4,701      6,036      5,696      2,499      2,453
                                                                  ---------  ---------  ---------  ---------  ---------
  Net loss......................................................  $  (4,701) $  (6,036) $  (2,875) $  (2,494) $  (1,541)
                                                                  ---------  ---------  ---------  ---------  ---------
                                                                  ---------  ---------  ---------  ---------  ---------
  Pro forma net loss per share (2)..............................                        $   (0.63)            $   (0.33)
                                                                                        ---------             ---------
                                                                                        ---------             ---------
  Pro forma weighted average shares outstanding (2).............                        4,536,481             4,676,327
                                                                                        ---------             ---------
                                                                                        ---------             ---------
</TABLE>
 
<TABLE>
<CAPTION>
                                                                                     MARCH 31, 1996
                                                                        -----------------------------------------
                                                                                                     PRO FORMA
                                                                         ACTUAL    PRO FORMA (3)  AS ADJUSTED (4)
                                                                        ---------  -------------  ---------------
<S>                                                                     <C>        <C>            <C>
BALANCE SHEET DATA:
  Cash and cash equivalents...........................................  $      27   $       177     $    27,227
  Working capital.....................................................       (800)         (650)         26,400
  Total assets........................................................      1,087         1,237          28,287
  Long-term obligations...............................................      1,214           232             232
  Deficit accumulated during development stage........................    (16,215)      (16,215)        (16,215)
  Total stockholders' equity (deficit)................................     (1,291)         (159)         26,891
</TABLE>
 
- ------------------
(1) Based on shares outstanding as of May 31, 1996 and an assumed initial public
    offering price of $12.00 per share.  Excludes: (i) 606,625 shares of  Common
    Stock  issuable upon  exercise of  stock options  outstanding as  of May 31,
    1996, with a weighted average exercise price of $6.62 per share; (ii) 26,126
    shares of Common Stock issuable upon exercise of warrants outstanding as  of
    May  31, 1996, with an exercise price  of $9.18 per share; and (iii) 661,700
    additional shares of Common Stock reserved for issuance under the  Company's
    stock   plans.  See  "Capitalization,"  "Management   --  Stock  Plans"  and
    "Description of Capital Stock."
 
(2) See Note 1 of Notes  to Financial Statements for information concerning  the
    computation of pro forma net loss per share.
 
(3)  Gives pro forma effect, assuming an initial public offering price of $12.00
    per share, to: (i) the conversion of a convertible debenture and  promissory
    note held by Interneuron into Common Stock upon the closing of the Offering;
    and  (ii) the purchase by The Ohio University Foundation of 25,000 shares of
    Common Stock at a  price of $6.00  per share, pursuant  to a stock  purchase
    right. See "Capitalization" and "Certain Transactions."
 
(4)  Pro  forma as  adjusted to  give effect  to  the issuance  and sale  of the
    2,500,000 shares of Common Stock  offered hereby (after deducting  estimated
    underwriting  discounts and  commissions and  the estimated  expenses of the
    Offering) and  the receipt  and application  of the  estimated net  proceeds
    therefrom  at an assumed initial public  offering price of $12.00 per share.
    See "Use of Proceeds" and "Capitalization."
 
                               ------------------
 
   
    EXCEPT AS OTHERWISE  NOTED, ALL  INFORMATION IN  THIS PROSPECTUS,  INCLUDING
FINANCIAL  INFORMATION, SHARE AND PER SHARE  DATA: (I) REFLECTS THE CONSUMMATION
OF A 1-FOR-2 REVERSE STOCK  SPLIT TO BE EFFECTED  PRIOR TO OR CONCURRENTLY  WITH
THE  OFFERING; (II) REFLECTS THE AUTOMATIC  CONVERSION OF ALL OUTSTANDING SHARES
OF PREFERRED STOCK INTO  AN AGGREGATE OF 1,774,014  SHARES OF COMMON STOCK  UPON
THE  CLOSING OF THE  OFFERING; (III) REFLECTS THE  CONVERSION OF THE CONVERTIBLE
DEBENTURE AND PROMISSORY NOTE HELD BY  INTERNEURON INTO AN AGGREGATE OF  142,026
SHARES  OF COMMON STOCK  (BASED ON THE  OUTSTANDING BALANCE AS  OF MAY 31, 1996)
UPON THE  CLOSING  OF THE  OFFERING;  (IV) REFLECTS  THE  PURCHASE BY  THE  OHIO
UNIVERSITY  FOUNDATION OF 25,000 SHARES OF COMMON  STOCK AT A PRICE OF $6.00 PER
SHARE, PURSUANT TO  A STOCK PURCHASE  RIGHT; AND (V)  ASSUMES AN INITIAL  PUBLIC
OFFERING  PRICE  OF  $12.00  PER  SHARE AND  NO  EXERCISE  OF  THE UNDERWRITERS'
OVER-ALLOTMENT OPTION.  SEE  "CERTAIN  TRANSACTIONS,"  "DESCRIPTION  OF  CAPITAL
STOCK" AND "UNDERWRITING."
    
 
                                       4
<PAGE>
                                  RISK FACTORS
 
    IN  ADDITION  TO THE  OTHER INFORMATION  IN  THIS PROSPECTUS,  THE FOLLOWING
FACTORS SHOULD BE CONSIDERED CAREFULLY  BY POTENTIAL INVESTORS IN EVALUATING  AN
INVESTMENT  IN  THE  SHARES  OF COMMON  STOCK  OFFERED  HEREBY.  THIS PROSPECTUS
CONTAINS, IN ADDITION TO HISTORICAL INFORMATION, FORWARD-LOOKING STATEMENTS THAT
INVOLVE RISKS  AND  UNCERTAINTIES. THE  COMPANY'S  ACTUAL RESULTS  COULD  DIFFER
SIGNIFICANTLY FROM THOSE DISCUSSED IN THE FORWARD-LOOKING STATEMENTS.
 
    UNCERTAINTIES  RELATING TO TECHNOLOGICAL APPROACH OF  THE COMPANY.  To date,
the Company has not  developed or commercialized any  products. There can be  no
assurance  that the Company's functional approach  to genomics will enable it to
discover genes,  receptors or  other  proteins with  functions relevant  to  the
treatment  of diseases. The Company's  discovery programs are primarily directed
to complex diseases. There is  limited scientific understanding relating to  the
role of genes, receptors and other proteins in these diseases and relatively few
products  based on genetic discoveries have been developed and commercialized to
date. Accordingly,  even if  the  Company is  successful in  identifying  genes,
receptors  or other proteins associated with  specific diseases, there can be no
assurance that the Company  will be successful in  marketing its discoveries  to
pharmaceutical   companies  for  use  in  the  development  of  therapeutic  and
diagnostic products or  that any  such resulting products  will be  successfully
commercialized.
 
    The  development of products based on the Company's discoveries also will be
subject to the risks of failure inherent in the development of products based on
new technologies. These  risks include  the possibility that  any such  products
will be found to be ineffective or toxic, or otherwise fail to receive necessary
regulatory approvals; that any such products will be difficult to manufacture on
a commercial scale or will be uneconomical to market; that proprietary rights of
third parties will preclude the Company or its strategic partners from marketing
any  such products;  or that  third parties  will market  superior or equivalent
products. As a result, there can be no assurance that the Company's research and
development activities or those of  its licensees and collaborators will  result
in  any  commercially  viable  products.  See  "--  Uncertainty  of  Patents and
Proprietary Rights," "Business  -- Progenitor's  Functional Genomics  Approach,"
"--   Progenitor's   Discovery   Programs"  and   "--   Strategic  Collaboration
Agreements."
 
    Genomics,   biotechnology,   developmental   biology   and    pharmaceutical
technologies  have undergone and  are expected to continue  to undergo rapid and
significant change. The Company's  future success will depend  in large part  on
its   ability  to  maintain  a  competitive   position  with  respect  to  these
technologies. Rapid  technological developments  by the  Company or  others  may
result  in compounds, products or processes becoming obsolete before the Company
recovers any  expenses it  incurs in  connection with  the development  of  such
products. See "-- Intense Competition; Rapid Technological Change" and "Business
- -- Competition."
 
    HISTORY OF OPERATING LOSSES; ANTICIPATION OF FUTURE LOSSES.  Progenitor is a
development stage company that commenced operations in May 1992. As of March 31,
1996,  the Company had an accumulated deficit of approximately $16.2 million and
a working  capital  deficit of  $800,000.  Losses have  resulted  from  expenses
incurred  in the  Company's research and  development programs and,  to a lesser
extent, from  general  and administrative  and  interest expenses.  Neither  the
Company  nor any  of its collaborative  partners has yet  developed any products
which have entered clinical trials or generated any revenues to the Company.  To
date,  all of the Company's revenues  have resulted from payments from strategic
partners and a development grant from a governmental agency. The Company expects
to incur substantial additional losses over  the next several years and  expects
cumulative  losses  to increase  substantially as  it  expands its  research and
development activities.  Payments  from collaborative  partners,  license  fees,
payments  under governmental grants and investment income, in each case, if any,
are expected to be the only sources  of revenue for the foreseeable future.  The
Company  has not yet  generated any revenues from  the achievement of milestones
under its collaborative agreements. Royalties or other revenues from  commercial
sales  of products are not expected for a number of years, if at all. To achieve
profitable
 
                                       5
<PAGE>
operations,  Progenitor,  alone  or  with  others,  must  successfully  discover
medically relevant genes, receptors or related proteins and thereafter use these
discoveries  to  develop  products,  conduct  preclinical  studies  and clinical
trials, obtain  required  regulatory  approvals  and  successfully  manufacture,
introduce and market such products, of which there can be no assurance. The time
required  to reach or sustain profitability is highly uncertain and there can be
no assurance  that  the Company  will  be able  to  achieve profitability  on  a
sustained basis, if at all. Moreover, if profitability is achieved, the level of
profitability  cannot be  predicted and may  vary significantly  from quarter to
quarter. See "Management's  Discussion and Analysis  of Financial Condition  and
Results of Operations."
 
    EARLY    STAGE    OF    DEVELOPMENT;    UNCERTAINTY    OF    FINAL   PRODUCT
DEVELOPMENT.  Significant  discovery, research and  development efforts will  be
required  prior  to the  time any  of  the Company's  genes, receptors  or other
protein discoveries may develop  into product candidates  or result in  products
that  may be brought to the market, if  at all. Products, if any, resulting from
the  Company's  research  and  development  programs  are  not  expected  to  be
commercially  available for a number of years, if at all. Significant additional
research and development efforts and extensive preclinical studies and  clinical
trials  will be required  prior to submission of  any regulatory application for
commercial use. There can be no  assurance that the Company or any  collaborator
or  licensee will  be permitted  to undertake  clinical trials  of any potential
products, if developed, that sufficient numbers of patients can be enrolled  for
such  trials, or  that such clinical  trials will demonstrate  that the products
tested are safe and efficacious. Even  if clinical trials are successful,  there
can be no assurance that the Company or any collaborator or licensee will obtain
regulatory approval for any indication, that an approved product can be produced
and  distributed in commercial quantities at reasonable costs or gain acceptance
for use by  physicians and other  health care providers,  or that any  potential
products  will be successfully marketed at  prices that would permit the Company
to operate profitably. The failure of any of these events to occur could have  a
material  adverse  effect on  the  Company's business,  financial  condition and
results of operations. See "Business -- Progenitor's Discovery Programs" and "--
Government Regulation."
 
    NEED FOR ADDITIONAL CAPITAL; UNCERTAINTY OF ADDITIONAL FUNDING.  The Company
expects negative cash flow from operations  to continue and to increase for  the
foreseeable  future. The  Company will  require substantial  additional funds to
continue research  and development,  conduct  preclinical studies  and  clinical
trials,  conduct  activities  relating  to commercialization  of  rights  it has
retained  in   strategic   collaboration   agreements,  if   any,   and   expand
administrative  capabilities. The Company estimates that  at its planned rate of
spending, any existing cash and cash equivalents, together with the net proceeds
from the Offering and  the interest income thereon,  will be sufficient to  meet
its  capital  requirements for  at least  the next  18 months.  There can  be no
assurance, however, that the Company's  assumptions regarding its future  levels
of  expenditures and operating losses will  prove accurate. The Company's future
capital requirements  will  depend on  many  factors, including  the  scientific
progress  in and the breadth of the Company's research and development programs;
the results of research and development, preclinical studies and clinical trials
conducted by the Company or its collaborative partners or licensees, if any; the
acquisition and licensing of products and technologies; the Company's ability to
establish and maintain relationships with corporate and academic  collaborators;
competing  technological and market developments; the time and costs involved in
filing, prosecuting, defending  and enforcing patent  and intellectual  property
claims;  the receipt of licensing  or milestone fees from  any current or future
collaborative  arrangements,   if   established;  the   continued   funding   of
governmental  research  grants; the  timing of  regulatory approvals;  and other
factors. To the extent undertaken by the Company, the time and costs involved in
conducting  preclinical  studies   and  clinical   trials,  seeking   regulatory
approvals,  and scaling-up  manufacturing and  commercialization activities also
would increase the Company's capital needs.
 
    The Company  will  need to  raise  substantial additional  capital  to  fund
operations.  Prior to this Offering, Interneuron has funded substantially all of
the Company's  operations.  Interneuron,  however, is  under  no  obligation  to
provide,  and the  Company does  not expect  that Interneuron  will provide, any
additional funds in the future. The  Company intends to seek additional  funding
through public or
 
                                       6
<PAGE>
private equity or debt financing and collaborative arrangements. There can be no
assurance  that additional financing will be  available when needed, or that, if
available, such financing will be available on terms acceptable to the  Company.
If  additional  funds  are  raised by  issuing  equity  securities,  dilution to
existing stockholders will  result. In  addition, in the  event that  additional
funds  are  obtained  through  arrangements  with  collaborative  partners, such
arrangements may require  the Company  to relinquish  rights to  certain of  its
technologies  or potential products  that it would otherwise  seek to develop or
commercialize itself. If funding is insufficient at any time in the future,  the
Company  may be required  to delay, scale back  or eliminate some  or all of its
research  and  development  programs  or  cease  operations.  See  "Management's
Discussion  and Analysis  of Financial  Condition and  Results of  Operations --
Liquidity and Capital Resources."
 
    DEPENDENCE ON COLLABORATORS.   The  Company's strategy  for development  and
commercialization  of drugs and other products from its discoveries depends upon
the formation of various corporate  collaborations. The Company expects to  rely
on  collaborative partners to  research and develop  potential products, conduct
clinical trials, obtain  regulatory approvals,  and manufacture  and market  any
resulting products. The Company has entered into agreements with Chiron and Novo
Nordisk. The Company's revenues will be dependent on the success of the products
developed  by these  and any future  collaborative partners. The  failure of the
Company's collaborative partners to develop, obtain regulatory approval of,  and
market  products incorporating the  Company's discoveries would  have a material
adverse effect on  the Company's  business, financial condition  and results  of
operations. There can be no assurance that any collaborative partner will commit
sufficient    development    resources,   technology,    regulatory   expertise,
manufacturing, marketing and other  resources towards developing, promoting  and
commercializing  products  incorporating  the  Company's  discoveries.  Further,
competitive conflicts may  arise among  these third parties  that could  prevent
them  from  working cooperatively  with the  Company. The  amount and  timing of
resources devoted  to these  activities  by such  parties  could depend  on  the
achievement  of milestones  by the Company  and generally will  be controlled by
such partners.  In addition,  the Company's  collaborative agreements  generally
provide  the Company's collaborator with the right to terminate the agreement in
part or  in  full  under  certain  circumstances.  Any  such  termination  would
substantially  reduce the  likelihood that  the collaborative  product candidate
will be developed,  would obtain  regulatory approvals and  be manufactured  and
successfully  commercialized and any  such termination could,  therefore, have a
material adverse  effect  on the  Company's  business, financial  condition  and
results  of operations. The Company's royalties  from sales of products licensed
to collaborators, if any, may be less  than the revenues the Company could  have
generated  had it commercialized  and marketed products itself.  There can be no
assurance that  the Company  will be  successful in  establishing additional  or
maintaining existing collaborative arrangements, that any collaborative partners
will  be  successful  in developing  and  commercializing products  or  that the
Company will generate revenues from royalties sufficient to offset the Company's
significant  investment  in  research  and  development  and  other  costs.  See
"Business -- Strategic Collaboration Agreements" and "-- License Agreements."
 
    INTENSE  COMPETITION; RAPID TECHNOLOGICAL CHANGE.   Research in the field of
genomics is highly competitive. Competitors of the Company in the genomics  area
include, among others, public companies such as Genome Therapeutics Corporation,
Human   Genome   Sciences,  Inc.,   Incyte  Pharmaceuticals,   Inc.,  Millennium
Pharmaceuticals,  Inc.  ("Millennium"),  Myriad   Genetics,  Inc.  and   Sequana
Therapeutics,  Inc.,  as  well  as private  companies  and  major pharmaceutical
companies and  universities and  other  research institutions,  including  those
receiving  funding from the  federally funded Human Genome  Project. A number of
entities are attempting to rapidly identify and patent randomly-sequenced  genes
and  gene fragments.  In addition,  certain other  entities are  pursuing a gene
identification, characterization and product development strategy based on  gene
mapping.  The  Company's  competitors  may  discover,  characterize  or  develop
important genes in advance of the  Company, which could have a material  adverse
effect on any related Company discovery program. The Company expects competition
to  intensify in genomics research  as technical advances in  the field are made
and become more widely known.
 
                                       7
<PAGE>
   
    In  addition,  the  Company  faces,  and  will  continue  to  face,  intense
competition from pharmaceutical and biotechnology companies, as well as academic
and  research institutions and governmental agencies.  The Company is subject to
significant competition from organizations that are pursuing the same or similar
technologies as those  which constitute the  Company's discovery platforms,  and
from  organizations that are pursuing pharmaceutical  or other products that are
or may be  competitive with the  Company's or its  collaborators' or  licensees'
potential  products. Many of  the organizations competing  with the Company have
greater  capital  resources,   larger  research  and   development  staffs   and
facilities,  greater  experience in  drug  discovery and  development, obtaining
regulatory approvals  and  pharmaceutical  product  manufacturing,  and  greater
marketing capabilities than the Company.
    
 
    The Company also is aware of a number of companies and institutions that are
developing or considering the development of potential gene-based and cell-based
treatments,  including early-stage gene  therapy companies, large pharmaceutical
companies, academic  and research  institutions, government  agencies and  other
health care providers. Many of these entities are more advanced than the Company
in their product development programs for gene and cell-based therapies and have
more experience with regulatory agencies and clinical trials. The fields of gene
and cell-based therapies are new and many competitive approaches are being taken
to  discover  practical  means by  which  these  technologies can  be  made into
products.  Rapid  technologic  advances  could  result  in  actual  or  proposed
technologies,  products or processes  of the Company  becoming obsolete prior to
successful commercialization.
 
    The Company is  and will continue  to be reliant  on strategic partners  for
support  of  its  programs,  including  preclinical  and  clinical  development,
manufacturing and  marketing of  its  initial products.  Each of  the  Company's
present  and future partners is  conducting multiple product development efforts
within each disease or technology area that is the subject of the alliance  with
the  Company. Any product candidate or technology of the Company, therefore, may
be subject to internal competition with a potential product under development or
technology platform under evaluation by  a strategic partner. See  "--Dependence
on   Collaborators,"  "Business   --  Background   --  Overview   of  Genomics,"
"-- Progenitor's Functional Genomics Approach" and "-- Competition."
 
    UNCERTAINTY OF PATENTS AND PROPRIETARY  RIGHTS.  The Company's success  will
depend  to a significant  extent on its  ability to obtain  and enforce patents,
maintain  trade  secret  protection  and  operate  without  infringing  on   the
proprietary   rights  of  third   parties.  Because  the   patent  positions  of
biotechnology  and  pharmaceutical  companies   can  be  highly  uncertain   and
frequently  involve complex legal  and factual questions,  the breadth of claims
allowed in  biotechnology and  pharmaceutical  patents or  their  enforceability
cannot be predicted. Commercialization of pharmaceutical products can be subject
to  substantial delays as a result of the time required for product development,
testing and regulatory approval. The value of any patents issued or licensed  to
the Company may depend upon the remaining term of patent protection available at
the time products that utilize the patented technology are commercialized.
 
    The  Company actively  pursues a policy  of seeking patent  protection for a
number of its  proprietary products  and technologies.  Progenitor has  licensed
from  Ohio  University  one U.S.  patent  and pending  U.S.  patent applications
relating to  stem cell  technology  and to  gene  delivery technology  (and  has
received   a  notice  of  allowance  relating  to  a  gene  delivery  technology
application), along with certain  corresponding foreign patent applications  and
one  issued foreign  patent. Progenitor has  filed six  U.S. patent applications
relating to certain leptin receptors  (including various isoforms of the  leptin
receptor),  including patent applications filed  in September and December 1994.
In March 1996,  Progenitor's international patent  application covering  certain
leptin  receptors  was  published.  The  Company  believes  that  there  may  be
significant litigation regarding patent  and other intellectual property  rights
relating  to leptin and  leptin receptors. The Company  is aware that Millennium
has filed a patent application relating to a receptor for leptin and its use  in
obesity  applications,  and has  licensed to  Hoffmann-La  Roche Inc.  rights to
develop certain  therapeutics  for obesity  using  Millennium's discovery  of  a
leptin receptor.
 
                                       8
<PAGE>
   
    Millennium  has recently filed  a "Protest" in the  United States Patent and
Trademark Office (the  "USPTO") in connection  with the Progenitor  applications
relating  to leptin receptors, including the applications filed in September and
December 1994. A  Protest is an  available procedure sometimes  used by a  third
party  to provide the patent examiner  who is reviewing the involved application
or applications with what the third  party believes to be relevant  information.
The  Protest  procedure  does  not  afford  any  right  to  the  third  party to
participate in the patent prosecution process  beyond the filing of its  written
Protest.  Millennium's  Protest  primarily  argues that  any  claims  allowed to
Progenitor should not be so broad as to cover Millennium's own leptin receptor.
    
 
   
    There  can  be  no  assurance  that  Millennium's  patent  application,   or
additional patent applications filed by Millennium or others, will not result in
issued  patents covering a leptin receptor, the leptin protein or other ligands,
or any of their  respective uses, including obesity.  There can be no  assurance
that  the invention by Millennium will be  accorded an invention date later than
Progenitor's invention date, that  any patent will issue  to Progenitor or  that
any  such patent  issued to  Progenitor would  be broad  enough to  cover leptin
receptors of Millennium or others. Progenitor's failure to obtain a patent on  a
leptin  receptor,  or its  failure to  obtain  a patent  that covers  the leptin
receptors of Millennium or others, or the issuance of a patent to a third  party
covering a leptin receptor, the leptin protein or other ligands, or any of their
respective  uses, including obesity, could have a material adverse effect on the
Company's business, financial condition and results of operations.
    
 
    A number of other groups are  attempting to identify partial gene  sequences
and  full-length genes, the functions of  which have not been characterized. The
public availability  of partial  gene sequence  information before  the  Company
applies  for  patent  protection  on  a  corresponding  full-length  gene  could
adversely affect the Company's ability to obtain patent protection with  respect
to  such gene. To the extent any patents  issue to other parties on such partial
or full-length  genes, and  as other  patents issue  with the  expansion of  the
biotechnology  industry,  the risk  increases  that the  potential  products and
processes of the Company or its  collaborative partners may give rise to  claims
of patent infringement.
 
   
    The  patent positions  of pharmaceutical and  biotechnology firms, including
the Company, are uncertain and involve  complex legal and factual questions  for
which  important legal principles are largely unresolved, particularly in regard
to human therapeutic  uses. Substantial periods  of time pass  before the  USPTO
responds  to patent applications. In addition,  the coverage claimed in a patent
application  can  be   significantly  reduced   before  a   patent  is   issued.
Consequently,  the Company does  not know whether  any of its  pending or future
patent applications will result  in the issuance of  patents or, if any  patents
are  issued,  whether  the  patents will  be  subjected  to  further proceedings
limiting their  scope, and  whether they  will provide  significant  proprietary
protection  or competitive  advantage, or  will be  circumvented or invalidated.
Because patent applications in the United States are maintained in secrecy until
patents issue and patent applications  in certain other countries generally  are
not  published  until  more than  18  months  after they  are  filed,  and since
publication of discoveries in scientific or patent literature often lags  behind
actual  discoveries, the Company cannot  be certain that it  or any licensor was
the first creator of inventions covered  by pending patent applications or  that
it  or  such  licensor  was  the  first  to  file  patent  applications  on such
inventions.
    
 
    There can be no  assurance that the Company's  patents, if issued, would  be
held  valid or enforceable by a court  or that such patents would cover products
or  technologies  of  the   Company's  competitors.  Competitors  or   potential
competitors  may have filed applications for or received patents, and may obtain
additional patents and  proprietary rights  relating to  compounds or  processes
competitive  with those of  the Company. To protect  its proprietary rights, the
Company may be required to  participate in interference proceedings declared  by
the  USPTO to determine priority of invention, which could result in substantial
cost to the Company. Moreover, even if the Company's patents issue, there can be
no assurance that they  will provide sufficient  proprietary protection or  will
not  be later limited, circumvented or invalidated. Accordingly, there can be no
assurance that  the  Company  will develop  proprietary  technologies  that  are
patentable,  that the Company's patent applications will result in patents being
 
                                       9
<PAGE>
issued or that, if  issued, patents will  afford protection against  competitors
with  similar technology or  products, nor can  there be any  assurance that the
Company's patents will be held valid by a court of competent jurisdiction.
 
    In addition to patent protection, the  Company also relies to a  significant
extent  upon  trade  secret  protection  for  its  unpatented  confidential  and
proprietary  information  including   many  of  the   Company's  key   discovery
technologies,  such  as its  proprietary methods  of isolating  and manipulating
murine ES cells. There  can be no assurance  that others will not  independently
develop  substantially  equivalent  proprietary  information  and  techniques or
otherwise  gain  access  to  the  Company's  trade  secrets  or  disclose   such
technology.  To protect its  trade secrets, the  Company requires its employees,
consultants, scientific  advisors and  parties  to collaborative  agreements  to
execute  confidentiality  agreements upon  the  commencement of  employment, the
consulting relationship or the  collaboration with the Company.  In the case  of
employees,  the agreements also provide that  all inventions resulting from work
performed by them while employed by  the Company will be the exclusive  property
of  the Company. There can be no  assurance, however, that these agreements will
provide meaningful  protection  of  the  Company's  trade  secrets  or  adequate
remedies  in the  event of unauthorized  use or disclosure  of such information,
that the  Company  can  meaningfully  protect  its  rights  in  such  unpatented
proprietary  technology through other means, that any obligation to maintain the
confidentiality  of  such  proprietary  technology  will  not  be  breached   by
employees,  consultants,  advisors, collaborative  partners  or others,  or that
others will not independently  develop substantially equivalent technology.  The
loss  of  trade  secret  protection  of  any  of  the  Company's  key  discovery
technologies would  materially and  adversely affect  the Company's  competitive
position  and could  have a material  adverse effect on  the Company's business,
financial condition and results of operations. Finally, disputes may arise as to
the ownership of proprietary rights to the extent that outside collaborators  or
consultants  apply technological information developed  independently by them or
others to Company projects or apply Company technology to other projects and, if
adversely determined, such disputes could have a material adverse effect on  the
Company's business, financial condition and results of operations.
 
    The  Company may incur substantial costs if  it is required to defend itself
in patent suits brought by third parties or if the Company initiates such a suit
to enforce the Company's patents or to determine the scope and validity of other
parties' proprietary  rights.  Any  legal  action against  the  Company  or  its
collaborators  or licensees  claiming damages  and seeking  to enjoin commercial
activities relating to the affected products and processes could, in addition to
subjecting the Company to potential  liability for damages, require the  Company
or  its collaborators or licensees  to obtain a license  or licenses in order to
continue to manufacture or market the affected products and processes. There can
be no assurance that the Company or its collaborators or licensees would prevail
in any such action or that any license required under any such patents would  be
made  available on commercially acceptable terms, if at all. Any adverse outcome
of such  litigation  could have  a  material  adverse effect  on  the  Company's
business,  financial condition  and results of  operations. In  addition, if the
Company becomes  involved in  such litigation,  it could  consume a  substantial
portion  of the  Company's managerial  and financial  resources. The  Company is
unable to predict  how courts  will resolve any  future issues  relating to  the
validity and scope of its patents should they be challenged.
 
    It  is uncertain whether any third-party patents will require the Company to
alter its products or  processes, obtain licenses,  cease certain activities  or
pay substantial damages. If any licenses are required, there can be no assurance
that  the  Company will  be  able to  obtain  any such  license  on commercially
acceptable terms, if  at all. Failure  by the Company  or its collaborators  and
licensees  to obtain a  license to any technology  required to commercialize the
Company's discoveries  may  have a  material  adverse effect  on  the  Company's
business,  financial  condition  and  results of  operations.  See  "Business --
Patents and Proprietary Rights."
 
    UNCERTAINTIES  RELATED  TO  CLINICAL  TRIALS.    Before  seeking  regulatory
approvals  for  the  commercial  sale  of any  products  that  may  be developed
incorporating the  Company's  discoveries,  the  Company  or  its  collaborative
partners  will  be  required  to  demonstrate  through  preclinical  studies and
clinical trials that such products are safe and effective for use in the  target
indications. To date, no product candidates
 
                                       10
<PAGE>
incorporating  the  Company's  discoveries  have  entered  clinical  trials. The
results from preclinical studies and early clinical trials may not be indicative
of results that will  be obtained in  large-scale testing, and  there can be  no
assurance  that any clinical trials,  if undertaken, will demonstrate sufficient
safety and efficacy to obtain the requisite regulatory approvals or will  result
in  marketable products. Clinical trials also  are often conducted with patients
having advanced  stages  of  disease.  During the  course  of  treatment,  these
patients  can die or suffer  other adverse medical effects  for reasons that may
not be related to the product candidate being tested but which can  nevertheless
affect  clinical  trial  results. A  number  of companies  in  the biotechnology
industry have suffered  significant setbacks in  advanced clinical trials,  even
after  achieving promising results  in earlier trials.  If products developed by
the Company or its collaborative partners are not shown to be safe and effective
in clinical trials, the resulting delays in developing other product  candidates
and  conducting related preclinical testing and  clinical trials, as well as the
need for  additional financing,  would have  a material  adverse effect  on  the
Company's business, financial condition and results of operations. See "Business
- -- Progenitor's Discovery Programs."
 
    GOVERNMENT  REGULATION;  NO  ASSURANCE  OF REGULATORY  APPROVAL.    Prior to
marketing, any  new  drug or  other  product developed  by  the Company  or  its
collaborative  partners must undergo an extensive regulatory approval process in
the United States and other  countries. This regulatory process, which  includes
preclinical studies and clinical trials, and may include post-marketing studies,
of  each product candidate  to establish its safety  and efficacy, usually takes
many years and  require the  expenditure of  substantial resources.  Preclinical
tests  include laboratory evaluations and  will require animal studies conducted
in accordance the United States  Food and Drug Administration's ("FDA")  current
Good Laboratory Practices ("cGLP") regulations to assess the product's potential
safety  and efficacy. Data obtained from preclinical studies and clinical trials
are susceptible to varying  interpretations that could  delay, limit or  prevent
regulatory  approval. Delays  or rejections also  may be  encountered based upon
changes in  FDA policies  for drug  or biologic  approval during  the period  of
product  development  and FDA  regulatory review  of  each new  drug application
("NDA") submitted in the case of  new pharmaceutical agents, or product  license
application  ("PLA")  in  the  case of  biologics.  Product  development  of new
pharmaceuticals is highly uncertain, and unanticipated developments, clinical or
regulatory delays,  unexpected adverse  side effects  or inadequate  therapeutic
efficacy  could slow or  prevent the product development  efforts of the Company
and its collaborators or licensees, and have a materially adverse effect on  the
Company's  business, financial condition and results of operations. There can be
no assurance that regulatory  approval will be obtained  for any drugs or  other
products  developed by the  Company or its  collaborative partners or licensees.
Furthermore, regulatory approval may entail limitations on the indicated use  of
a  drug or other product. Because certain  of the products likely to result from
the Company's discovery programs involve the application of new technologies and
may be based upon a  new therapeutic approach, such  products may be subject  to
substantial additional review by various government regulatory authorities other
than  the FDA and, as a result, regulatory approvals may be obtained more slowly
than for  products using  conventional technologies.  Under current  guidelines,
proposals  to conduct clinical  research involving gene  therapy at institutions
supported by the National Institutes of  Health ("NIH") must be approved by  the
Recombinant  DNA  Advisory  Committee  ("RAC") and  the  NIH.  Furthermore, gene
therapies are relatively new technologies  and have not been tested  extensively
in  humans.  The regulatory  requirements governing  these products  and related
clinical procedures for their use are uncertain and are subject to change.
 
    Even if  regulatory  approval  is  obtained,  a  marketed  product  and  its
manufacturer  are subject to continuing review. Among the conditions for product
approval and  continued  marketing approval  is  that the  quality  control  and
manufacturing procedures of the Company or its collaborative partners conform to
the FDA's current good manufacturing practice ("cGMP") regulations which must be
followed  at all times. In complying  with cGMP requirements, manufacturers must
expend time,  money and  effort  on a  continuing  basis in  production,  record
keeping  and quality  control. Manufacturing  establishments, both  domestic and
foreign, are subject to inspection by or  under the authority of the FDA and  by
other  federal, state and  local agencies. Failure to  pass such inspections may
subject the manufacturer to
 
                                       11
<PAGE>
possible FDA actions  such as the  suspension of manufacturing,  seizure of  the
product,  withdrawal of approval or other regulatory sanctions. The FDA also may
require the manufacturer to recall a product from the market.
 
    Discovery of previously  unknown problems  with a product  may have  adverse
effects  on the Company's business, including withdrawal of the product from the
market.  Violations  of   regulatory  requirements  at   any  stage,   including
preclinical  studies and clinical trials, the approval process or post-approval,
may result in various adverse consequences  to the Company, including the  FDA's
delay  in approval or  refusal to approve  a product, withdrawal  of an approved
product from the  market or  the imposition  of criminal  penalties against  the
manufacturer   and  NDA  or  PLA  holder.  The  Company  has  not  submitted  an
investigational new drug application ("IND")  for any product candidate, and  no
product  candidate has been approved for  commercialization in the United States
or elsewhere. The Company intends to rely primarily on its strategic partners to
file INDs and generally direct the regulatory approval process. No assurance can
be given that  the Company  or any  of its strategic  partners will  be able  to
conduct clinical testing or obtain the necessary approvals from the FDA or other
regulatory authorities for any products. Failure to obtain required governmental
approvals will delay or preclude the Company's strategic partners from marketing
drugs  or other products developed by the Company or limit the commercial use of
such products  and  could  have  a material  adverse  effect  on  the  Company's
business,  financial  condition  and  results of  operations.  See  "Business --
Government Regulation."
 
    DEPENDENCE ON  KEY PERSONNEL.   The  Company is  highly dependent  upon  the
principal members of its scientific and management staff and the services of Dr.
Douglass  B.  Given, President  and Chief  Executive Officer,  and Dr.  H. Ralph
Snodgrass, Vice President, Research and Chief Scientific Officer, in particular.
The Company has no employment agreements with its executive officers other  than
Dr. Given. The loss of any of these persons could have a material adverse effect
on  the Company's  business, financial condition  and results  of operations. In
order to support the Company's existing operations, the Company will be required
to  hire  and  retain   additional  management,  administrative  and   financial
personnel,  including  a  chief  financial  officer.  Recruiting  and  retaining
qualified scientific personnel and advisors to perform research and  development
work  in the future also will be critical to the Company's success. There can be
no assurance that the Company will be able to attract and retain such  personnel
and   advisors  on  acceptable  terms   given  the  competition  among  numerous
pharmaceutical,  biotechnology  and  other  companies,  universities  and  other
research  institutions  for  experienced personnel  and  advisors.  In addition,
Progenitor's anticipated growth  and expansion are  expected to place  increased
demands  on the  Company's resources and  management skills. The  failure of the
Company's existing personnel to handle  such increased demands or the  Company's
failure  to attract  and to retain  additional personnel  with such capabilities
could have  a  material adverse  effect  on the  Company's  business,  financial
condition and results of operations. See "Management."
 
    DEPENDENCE  ON RESEARCH COLLABORATORS AND  SCIENTIFIC ADVISORS.  The Company
has relationships  with collaborators  at academic  and other  institutions  who
conduct  research in  cooperation with the  Company. Such  collaborators are not
employees of  the Company.  All of  the Company's  consultants are  employed  by
employers  other than the Company and may  have commitments to, or consulting or
advisory contracts with, other entities that may limit their availability to the
Company. As a result, the Company has limited control over their activities and,
except as otherwise required by its collaboration and consulting agreements, can
expect only  limited amounts  of their  time to  be dedicated  to the  Company's
activities. The potential success of the Company's discovery programs depends in
part  on  continued  collaborations  with  researchers  at  academic  and  other
institutions. There  can  be no  assurance  that the  Company  will be  able  to
negotiate   additional   acceptable   collaborations  at   academic   and  other
institutions or  that  its existing  collaborations  will be  maintained  or  be
successful.
 
    The Company's research collaborators and scientific advisors sign agreements
which  provide for confidentiality of  the Company's proprietary information and
results of studies. There can be no assurance, however, that the Company will be
able   to    maintain    the    confidentiality   of    its    technology    and
 
                                       12
<PAGE>
other  confidential information in connection  with every collaboration, and any
unauthorized dissemination of the Company's confidential information could  have
a  material adverse  effect on the  Company's business,  financial condition and
results of operations. See "-- Uncertainty of Patents and Proprietary Rights."
 
    LACK   OF    COMMERCIAL    MANUFACTURING,    DISTRIBUTION    OR    MARKETING
CAPABILITIES.    To  date,  the  Company  has  focused  its  hiring  on research
scientists and  a small  administrative and  managerial staff  and has  made  no
investment  in manufacturing, marketing or  product sales resources. The Company
does not generally expect to engage directly in manufacturing, marketing or sale
of products  and  intends  to  contract  with others  in  order  to  pursue  the
commercialization  of any products  developed based upon  its discoveries. There
can be  no  assurance  that  the  Company  will  be  able  to  enter  into  such
arrangements  on acceptable terms, if at all. The Company will be dependent to a
significant extent on  collaborative partners, licensees  or other entities  for
development,  manufacturing and commercialization of products. If the Company is
unable to obtain or retain third-party manufacturing on commercially  acceptable
terms,  its ability to commercialize products  may be delayed or foreclosed. The
Company's dependence upon third parties for the manufacture, marketing and sales
of products may adversely  affect the Company's ability  to develop and  deliver
products on a timely and competitive basis. The Company's current facilities and
staff  are inadequate for commercial production and distribution of products. If
the Company  chooses  in the  future  to  engage directly  in  the  development,
manufacturing  and marketing  of certain  products, it  will require substantial
additional funds, personnel and production and other facilities. There can be no
assurance that  any of  these resources  will  be available  to the  Company  on
acceptable terms, if at all. See "-- Need for Additional Capital; Uncertainty of
Additional Funding" and "-- Dependence on Collaborators."
 
    UNCERTAINTY    OF    HEALTH   CARE    REFORM   MEASURES    AND   THIRD-PARTY
REIMBURSEMENT.   The  business and  financial  condition of  pharmaceutical  and
biotechnology  companies  will  continue  to  be  affected  by  the  efforts  of
third-party  payors,  such  as  government  health  administration  authorities,
private  health insurers and other organizations,  to contain or reduce the cost
of health care. In the United States and in certain foreign jurisdictions  there
have  been, and the Company expects that there  will continue to be, a number of
legislative and regulatory proposals aimed  at changing the health care  system.
While  the Company  cannot predict  whether any  such legislative  or regulatory
proposals will be  adopted or the  effect that  such proposals may  have on  its
business,  the consideration or approval of such proposals could have a material
adverse effect on the  trading and market  price of the Common  Stock or on  the
Company's  ability  to  raise  capital  or  to  obtain  additional collaborative
partners, and  the adoption  of such  proposals could  have a  material  adverse
effect on the Company's business, financial condition and results of operations.
 
    In  both domestic  and foreign markets,  successful commercial  sales of the
Company's or its collaborators' or licensees' potential products will depend  in
part   on  the  availability   of  reimbursement  from   government  and  health
administrative authorities, private health insurers or other third-party payors.
Third-party payors are increasingly challenging the price and cost-effectiveness
of medical  products and  services.  Significant uncertainty  exists as  to  the
reimbursement  status of newly approved health care products. Future legislation
and regulations affecting  the pricing  of pharmaceuticals  could further  limit
reimbursement  for medical products and services. There can be no assurance that
any of the  Company's potential  products will be  considered cost-effective  or
that  adequate third-party reimbursement will be available to enable Progenitor,
its collaborators or licensees to maintain price levels sufficient to realize an
appropriate return  on its  investment. In  addition, the  trend toward  managed
health  care in  the United  States and  the concurrent  growth of  managed care
organizations, such as health maintenance organizations, which could control  or
significantly  influence the purchase  of health care  services and products, as
well as legislative  proposals to  reduce government  insurance programs,  could
result  in pricing  pressure for  any products  that might  be developed  by the
Company. If  adequate reimbursement  is  not provided  by government  and  other
third-party   payors  for  the  Company's  or  its  collaborative  partners'  or
licensees' potential products, there would be  a material adverse effect on  the
Company's business, financial condition and results of operations. See "Business
- -- Government Regulation."
 
                                       13
<PAGE>
    RISK  OF PRODUCT LIABILITY.  The testing, manufacture, marketing and sale of
pharmaceutical and other products entail  the inherent risk of liability  claims
or  product recalls and associated adverse  publicity. Clinical trials and sales
by  the  Company  or  its  collaborators  or  licensees  of  potential  products
incorporating  the  Company's discoveries  may expose  the Company  to potential
liability resulting from the use of  such products. Such liability might  result
from claims made directly by consumers or by regulatory agencies, pharmaceutical
companies  or others selling such products.  The Company currently has a limited
amount of  clinical  trial  and product  liability  insurance  coverage  through
Interneuron. The Company will seek to obtain its own coverage upon completion of
this  Offering  and  to maintain  and  appropriately increase  such  coverage as
clinical development of any  product candidates progresses and  if and when  its
products  are ready  to be  commercialized. There can  be no  assurance that the
Company will  be  able to  obtain  such insurance  or,  if obtained,  that  such
insurance  can be  acquired at  a reasonable  cost or  in sufficient  amounts to
protect the Company  against such  liability. Certain of  the Company's  license
agreements  require it to  indemnify licensors against  product liability claims
arising from products developed using the licensed technology. Also, certain  of
these  agreements  and other  collaboration  agreements require  the  Company to
maintain minimum levels of insurance  coverage. The failure to maintain  product
liability coverage, the occurrence of any product liability claim or a recall of
products  of the Company or its  collaborators or licensees, if developed, could
inhibit or prevent commercialization of products being developed by the  Company
and  could have a  material adverse effect on  the Company's business, financial
condition and results  of operations.  In addition,  to the  extent any  product
liability  claim exceeds  the amount  of any  insurance coverage,  the Company's
business, financial condition and results of operations could be materially  and
adversely affected. See "Business -- Strategic Collaboration Agreements" and "--
Product Liability Insurance."
 
    NO  PRIOR TRADING MARKET;  NO ASSURANCE OF  ACTIVE TRADING MARKET; POTENTIAL
VOLATILITY OF STOCK  PRICE. Prior  to this Offering,  there has  been no  public
market  for the Common Stock and there can be no assurance that an active public
market for the Common Stock will develop or be sustained after the Offering. The
initial public offering  price will be  determined through negotiations  between
the  Company  and  representatives  of  the Underwriters  and  there  can  be no
assurance that future market  prices for the Common  Stock will equal or  exceed
the  initial public offering price. The stock market has experienced significant
price and  volume  fluctuations  that  are  often  unrelated  to  the  operating
performance   of  particular  companies.  In  addition,  the  market  prices  of
securities of  other  biotechnology  companies  in the  past  have  been  highly
volatile  and the market price of the Company's Common Stock also may experience
such volatility. Factors such as the results of preclinical studies and clinical
trials by the Company or  its collaborative partners, licensees or  competitors,
evidence  of  the  safety  or  efficacy  of  products  of  the  Company  or  its
competitors, announcements  of  technological innovations  or  new  discoveries,
product  opportunities or products by the Company or its competitors, changes in
governmental regulations or third-party reimbursement policies, developments  in
patent   or  other  proprietary  rights  of  the  Company  or  its  competitors,
fluctuations in the Company's  operating results and  changes in general  market
conditions  for biotechnology stocks could have  an adverse impact on the future
price of the Common Stock. See "Underwriting."
 
   
    CONTROL  OF  COMPANY   BY,  AND  POTENTIAL   CONFLICTS  OF  INTEREST   WITH,
INTERNEURON.    Following  the  Offering,  Interneuron  will  own  51.2%  of the
outstanding  Common  Stock   of  the   Company  (48.7%   if  the   Underwriters'
over-allotment  option  is  exercised in  full).  Accordingly,  Interneuron will
continue to control  the election of  directors of the  Company and voting  with
respect  to matters submitted to stockholders, including extraordinary corporate
transactions such as  a merger  or sale of  substantially all  of the  Company's
assets.  In  addition,  the Company  and  Interneuron  intend to  enter  into an
intercompany services agreement that will provide among other things that in the
event of any future  equity offering by the  Company, Interneuron will have  the
right  to purchase  (at the  same price  and on  the same  terms as  such equity
offering) a  portion  of  the  shares  being  offered  so  as  to  maintain  its
fully-diluted  interest in Progenitor immediately prior to such equity offering,
subject to certain limitations. Interneuron's  ownership of a substantial  block
of  the Company's voting stock  could have the effect  of delaying or preventing
sales of additional securities of the Company or a sale of the Company or  other
change  of  control  supported by  the  other  stockholders of  the  Company. In
addition, the Company may be subject
    
 
                                       14
<PAGE>
to  various  risks  arising  from  Interneuron's  influence  over  the  Company,
including  conflicts  of interest  relating to  new business  opportunities that
could be pursued by the Company or by Interneuron and its other affiliates,  and
significant  corporate transactions for which  stockholder approval is required.
See "Certain  Transactions  --  Relationship with  Interneuron"  and  "Principal
Stockholders."
 
    ANTI-TAKEOVER CONSIDERATIONS.  After the Offering, the Company will have the
authority  to issue  up to 5,000,000  shares of  Preferred Stock in  one or more
series and  to fix  the powers,  designations, preferences  and relative  rights
thereof  without any further  vote or action by  the Company's stockholders. The
Company has no current  plans to issue shares  of Preferred Stock. However,  the
rights  of the holders of Common Stock will  be subject to, and may be adversely
affected by, the rights of the holders of any Preferred Stock that may be issued
in the future. The issuance of Preferred Stock would dilute the voting power  of
holders  of Common  Stock and  could have the  effect of  delaying, deferring or
preventing a change  in control  of the  Company. In  addition, all  outstanding
options under the Company's 1992 Stock Option Plan and 1996 Stock Incentive Plan
become  exercisable following  certain changes  in control  of the  Company. The
Company is subject  to the  provisions of Section  203 of  the Delaware  General
Corporation Law, which could delay or make more difficult a merger, tender offer
or  proxy contest involving the Company and  may have the effect of discouraging
takeovers which  could be  in  the best  interest  of certain  stockholders.  In
general,  the  statute  prohibits  a  publicly  held  Delaware  corporation from
engaging in  a "business  combination" with  an "interested  stockholder" for  a
period  of three  years after the  date of  the transaction in  which the person
became an interested stockholder, unless the business combination is approved in
a prescribed manner. There can be  no assurance that this provision, the  rights
of  option holders and the  Company's ability to issue  Preferred Stock will not
have an adverse effect on the market value of the Company's stock in the future.
See "Management -- Stock Plans" and "Description of Capital Stock."
 
    HAZARDOUS AND RADIOACTIVE  MATERIALS; ENVIRONMENTAL MATTERS.   Research  and
development  conducted by the  Company involves the  controlled use of hazardous
materials,  chemicals,  biological  materials  and  radioactive  compounds.  The
Company,   and  its  collaborative  partners,  as  applicable,  are  subject  to
international, federal, state and local laws and regulations governing the  use,
manufacture, storage, handling and disposal of such substances and certain waste
products.  The  Company  believes that  the  safety procedures  relating  to its
in-house research and development and production efforts comply in all  material
respects  with the standards currently prescribed  by such laws and regulations.
However, the risk  of accidental  contamination or injury  from these  materials
cannot  be completely eliminated. In the event  of such an accident, the Company
could be held  liable for any  resulting damages, and  any such liability  could
exceed  the Company's  resources. Moreover, there  can be no  assurance that the
Company's collaborative partners are and will continue to be in compliance  with
such  standards or that  the Company will  not be required  to incur significant
costs in the future to  comply with new or  modified standards. In such  events,
there  would be a  material adverse effect on  the Company's business, financial
condition and results of operations. See "Business -- Government Regulation."
 
    MANAGEMENT DISCRETION AS TO USE OF PROCEEDS.  The Company anticipates  using
the  net proceeds  of the  Offering primarily  to fund  research and development
activities, the expansion of facilities,  working capital and general  corporate
purposes.  The Company also may  use the net proceeds  of the Offering for other
purposes,  including  the   acquisition  of  technology   rights,  products   or
businesses. Accordingly, management will retain broad discretion over the use of
the  net proceeds of the Offering. There can be no assurance as to the timing or
application of such proceeds,  or that the application  thereof will not have  a
material adverse effect on the Company's future business, financial condition or
results of operations. See "Use of Proceeds."
 
    SHARES  ELIGIBLE  FOR  FUTURE SALE;  REGISTRATION  RIGHTS;  POSSIBLE ADVERSE
EFFECT ON STOCK  PRICE.  Sales  of substantial  amounts of Common  Stock in  the
public  market after the  Offering, or the possibility  of such sales occurring,
could adversely affect  prevailing market  prices for  the Common  Stock or  the
future  ability of the  Company to raise  capital through an  offering of equity
securities. Of the 7,293,819  shares to be outstanding  after the Offering,  the
2,500,000 shares of Common Stock offered hereby will be freely tradeable without
restriction  in the public market unless such shares are held by "affiliates" of
the
 
                                       15
<PAGE>
   
Company, as that term is defined in  Rule 144 under the Securities Act of  1933,
as  amended (the  "Securities Act").  The remaining  4,793,819 shares  of Common
Stock are restricted securities under the Securities Act and may be sold in  the
public  market only if they are registered or if they qualify for exemption from
registration under  Rule  144 or  701  under  the Securities  Act.  Pursuant  to
"lock-up"  agreements, all of the Company's executive officers and directors and
certain stockholders who collectively hold 771,529 of such restricted securities
have agreed not to offer, sell or  otherwise dispose of any of their  restricted
securities for a period of 180 days from the date of this Prospectus without the
prior  written consent of Vector Securities International, Inc. Interneuron will
hold 3,736,017  of such  restricted  securities and  has  agreed pursuant  to  a
lock-up  agreement  not  to offer,  sell  or  otherwise dispose  of  any  of its
restricted securities for a period of 365 days from the date of this  Prospectus
without  the prior written consent of  Vector Securities International, Inc. The
Company has also agreed  that it will  not offer, sell  or otherwise dispose  of
Common  Stock for a period of 180 days  from the date of this Prospectus without
the prior written consent of  Vector Securities International, Inc., other  than
pursuant  to  existing  stock  option plans.  Upon  termination  of  the lock-up
agreements, approximately  321,071 and  3,593,991 of  the restricted  securities
will  be  available  for  immediate  sale  beginning  181  days  and  366  days,
respectively, after the date of this Prospectus, in the public market subject to
certain volume, manner of sale and other limitations under Rule 144 and  385,450
shares  will be  eligible for  immediate sale  181 days  after the  date of this
Prospectus   without   limitation   under   Rule   144(k).   Vector   Securities
International,  Inc. may, at its sole discretion and at any time without notice,
release all or any portion of the shares subject to such lock-up agreements. The
Securities and  Exchange Commission  has  proposed revisions  to Rule  144,  the
effect  of which  would be  to shorten  the holding  periods under  Rule 144. If
enacted, these proposed revisions would increase, potentially substantially, the
number of shares that would be available for sale in the public market following
the expiration of the lock-up agreements. See "Description of Capital Stock" and
"Shares Eligible for Future Sale."
    
 
    After the Offering,  holders of  an aggregate  of 261,273  shares of  Common
Stock  will be entitled  to certain rights  with respect to  the registration of
such shares  for resale  under  the Securities  Act.  In addition,  the  Company
intends  to file  a Registration Statement  on Form  S-8 after the  date of this
Prospectus to register an aggregate of  606,625 shares of Common Stock  reserved
for  issuance upon exercise  of outstanding options and  an aggregate of 661,700
shares of Common Stock  reserved for issuance pursuant  to future option  grants
under  the  Company's  1992  Stock  Option Plan  and  the  Company's  1996 Stock
Incentive Plan.  If such  registrations cause  a large  number of  shares to  be
registered  and sold  in the  public market,  such sales  could have  an adverse
effect on the market price for  the Company's Common Stock. See "Description  of
Capital Stock -- Registration Rights" and "Shares Eligible for Future Sale."
 
    DILUTION.   Investors purchasing shares of Common Stock in the Offering will
incur immediate and substantial  dilution equal to  $8.28 per share.  Additional
dilution  is likely to occur upon the exercise of outstanding warrants and stock
options. See "Dilution."
 
    ABSENCE OF DIVIDENDS.  The Company has never declared or paid cash dividends
on its Common Stock. The Company currently intends to retain any future earnings
to finance the growth and development  of its business and, therefore, does  not
anticipate  paying any cash  dividends in the  foreseeable future. See "Dividend
Policy."
 
                                       16
<PAGE>
                                USE OF PROCEEDS
 
    The net  proceeds from  the sale  of the  2,500,000 shares  of Common  Stock
offered  hereby at an assumed initial public  offering price of $12.00 per share
are  estimated  to  be  approximately  $27.1  million  ($31.2  million  if   the
Underwriters'  over-allotment  option  is exercised  in  full),  after deducting
estimated underwriting discounts and commissions  and estimated expenses of  the
Offering payable by the Company.
 
    The  Company anticipates using the net proceeds of the Offering primarily to
fund research and development  activities, to fund  the expansion of  facilities
and  acquisition of  equipment, and  for working  capital and  general corporate
purposes. The Company may also use a portion of the net proceeds of the Offering
to acquire  technology  rights, products  or  businesses. No  such  transactions
involving a material amount of consideration are being negotiated as of the date
of  this Prospectus. The amounts actually  expended for each purpose will depend
on numerous factors, including the scientific progress in and the breadth of the
Company's research  and  development  programs;  the  results  of  research  and
development, preclinical studies and clinical trials conducted by the Company or
its  collaborative partners or licensees, if  any; the acquisition and licensing
of products and technologies;  the Company's ability  to establish and  maintain
relationships with corporate and academic collaborators; competing technological
and  market developments;  the time and  costs involved  in filing, prosecuting,
defending and enforcing patent and intellectual property claims; the receipt  of
licensing   or  milestone  fees   from  any  current   or  future  collaborative
arrangements, if  established; the  continued funding  of governmental  research
grants;  the  timing of  regulatory approvals,  if any;  and other  factors. The
Company estimates that, at its planned rate of spending, the net proceeds of the
Offering and the interest  income thereon, together with  any existing cash  and
cash  equivalents, will  be sufficient to  meet its capital  requirements for at
least the next 18 months. There can be no assurance, however, that the Company's
assumptions regarding its  future levels  of expenditures  and operating  losses
will  prove accurate. Pending such  uses, the Company intends  to invest the net
proceeds of the Offering in  investment grade, interest-bearing securities.  See
"Risk  Factors -- History  of Operating Losses;  Anticipation of Future Losses,"
"-- Need  for  Additional  Capital;  Uncertainty  of  Additional  Funding,"  "--
Management  Discretion as to  Use of Proceeds"  and "Management's Discussion and
Analysis of  Financial Condition  and  Results of  Operations --  Liquidity  and
Capital Resources."
 
                                DIVIDEND POLICY
 
    The  Company has  never declared  or paid  cash dividends  on shares  of its
Common Stock. The Company  currently intends to retain  any future earnings  for
its  business and,  therefore, does not  anticipate paying any  dividends in the
foreseeable future.
 
                                       17
<PAGE>
                                 CAPITALIZATION
 
   
    The following table sets forth the capitalization of the Company as of March
31, 1996  (i) on  an actual  basis as  if the  1-for-2 reverse  stock split  had
occurred  prior to  March 31,  1996; (ii) on  a pro  forma basis  to give effect
(assuming an initial public offering price of $12.00 per share) upon the closing
of the Offering  to (a) the  automatic conversion of  all outstanding shares  of
Preferred  Stock into an aggregate of 1,774,014  shares of Common Stock, (b) the
conversion of a convertible  debenture and promissory  note held by  Interneuron
into  an aggregate of  81,819 shares of  Common Stock (based  on the outstanding
balance as  of March  31, 1996)  and (c)  the purchase  by The  Ohio  University
Foundation  of 25,000  shares of  Common Stock  at a  price of  $6.00 per share,
pursuant to a stock purchase right; and  (iii) on a pro forma basis as  adjusted
to reflect the issuance and sale of the 2,500,000 shares of Common Stock offered
hereby (after deducting estimated underwriting discounts and commissions and the
estimated  expenses  of the  Offering),  and the  receipt  of the  estimated net
proceeds therefrom. See "Use of Proceeds" and "Description of Capital Stock."
    
 
   
<TABLE>
<CAPTION>
                                                                                         MARCH 31, 1996
                                                                              ------------------------------------
                                                                                                      PRO FORMA AS
                                                                               ACTUAL     PRO FORMA     ADJUSTED
                                                                              ---------  -----------  ------------
                                                                                         (IN THOUSANDS)
<S>                                                                           <C>        <C>          <C>
Long-term obligations.......................................................  $   1,214   $     232    $      232
Stockholders' equity:
  Preferred Stock, Series A, $.01 par value: 2,120,000 shares authorized;
   2,020,496 shares issued and outstanding, actual; no shares authorized,
   issued or outstanding, pro forma and pro forma as adjusted...............         20          --            --
  Preferred Stock, Series B, $.01 par value: 880,000 shares authorized;
   349,000 shares issued and outstanding, actual; no shares authorized,
   issued or outstanding, pro forma and pro forma as adjusted...............          3          --            --
  Preferred Stock, $.001 par value: 5,000,000 shares authorized; no shares
   issued or outstanding, actual, pro forma and pro forma as adjusted.......         --          --            --
  Common Stock, $.001 par value: 39,000,000 shares authorized; 2,852,779
   shares issued and outstanding, actual; 4,733,612 shares issued and
   outstanding, pro forma; 7,233,612 shares issued and outstanding, pro
   forma as adjusted (1)....................................................          3           5             7
  Additional paid-in capital................................................     14,898      16,051        43,099
  Deficit accumulated during development stage..............................    (16,215)    (16,215)      (16,215)
                                                                              ---------  -----------  ------------
    Total stockholders' equity (deficit)....................................     (1,291)       (159)       26,891
                                                                              ---------  -----------  ------------
      Total capitalization..................................................  $     (77)  $      73    $   27,123
                                                                              ---------  -----------  ------------
                                                                              ---------  -----------  ------------
</TABLE>
    
 
- ------------------------
(1) Excludes: (i) 606,625 shares of Common Stock issuable upon exercise of stock
    options outstanding as  of May 31,  1996, with a  weighted average  exercise
    price  of $6.62 per share; (ii) 26,126  shares of Common Stock issuable upon
    exercise of warrants outstanding as of May 31, 1996, with an exercise  price
    of  $9.18 per  share; and  (iii) 661,700  additional shares  of Common Stock
    reserved for issuance under  the Company's stock  plans. See "Management  --
    Stock Plans" and "Description of Capital Stock."
 
                                       18
<PAGE>
                                    DILUTION
 
   
    Pro  forma net tangible book  value per share is  equal to the Company's net
tangible assets (tangible assets of the Company less total liabilities)  divided
by  4,733,612 shares of Common Stock outstanding as of March 31, 1996 (as if the
1-for-2 reverse split of the Company's Common Stock had occurred prior to  March
31,  1996), assuming (i)  the automatic conversion of  all outstanding shares of
Preferred Stock into an aggregate of  1,774,014 shares of Common Stock upon  the
closing  of the  Offering, (ii)  the conversion  of a  convertible debenture and
promissory note held by Interneuron into an aggregate of 81,819 shares of Common
Stock upon the closing of the Offering  (based on the outstanding balance as  of
March  31, 1996)  and (iii)  the purchase by  The Ohio  University Foundation of
25,000 shares of Common Stock at a price of $6.00 per share, pursuant to a stock
purchase right. The pro forma net tangible book value of the Company as of March
31, 1996 was approximately negative $159,000 or negative $.03 per share. Without
taking into account any other changes in pro forma net tangible book value other
than to give effect to the sale of  the 2,500,000 shares of Common Stock in  the
Offering  (at an assumed initial public offering  price of $12.00 per share) and
the receipt of the estimated net proceeds therefrom, the pro forma net  tangible
book  value of the  Company as of  March 31, 1996  would have been approximately
$26.9 million or $3.72 per share.  This represents an immediate increase in  pro
forma net tangible book value of $3.75 per share to existing stockholders and an
immediate dilution of $8.28 per share to new investors. The following table sets
forth the per share dilution to new investors in the Offering:
    
 
<TABLE>
<S>                                                                   <C>        <C>
Assumed initial public offering price per share.....................             $   12.00
  Pro forma net tangible book value per share as of March 31,
   1996.............................................................  $    (.03)
  Increase per share attributable to new investors..................       3.75
                                                                      ---------
Pro forma net tangible book value per share after the Offering......                  3.72
                                                                                 ---------
Dilution per share to new investors.................................             $    8.28
                                                                                 ---------
                                                                                 ---------
</TABLE>
 
    The  following table summarizes, on a pro  forma basis as of March 31, 1996,
the differences between existing stockholders and new investors with respect  to
the  number of  shares of  Common Stock  purchased from  the Company,  the total
consideration paid and the average price  paid per share (at an assumed  initial
public  offering  price  of  $12.00 per  share  and  before  deducting estimated
underwriting discounts and commissions and estimated offering expenses):
 
<TABLE>
<CAPTION>
                                                 SHARES PURCHASED         TOTAL CONSIDERATION        AVERAGE
                                              -----------------------  --------------------------   PRICE PER
                                                NUMBER      PERCENT       AMOUNT        PERCENT       SHARE
                                              ----------  -----------  -------------  -----------  -----------
<S>                                           <C>         <C>          <C>            <C>          <C>
Existing stockholders.......................   4,733,612       65.0%   $  16,056,077       34.9%    $    3.39
New investors...............................   2,500,000       35.0       30,000,000       65.1         12.00
                                              ----------      -----    -------------      -----
    Total...................................   7,233,612      100.0%   $  46,056,077      100.0%
                                              ----------      -----    -------------      -----
                                              ----------      -----    -------------      -----
</TABLE>
 
    The foregoing tables reflect no exercise of outstanding options or  warrants
subsequent  to March 31, 1996. As of May 31, 1996, there were (i) 606,625 shares
of Common Stock  issuable upon  exercise of  outstanding stock  options, with  a
weighted  average exercise price of  $6.62 per share; and  (ii) 26,126 shares of
Common Stock issuable upon  exercise of outstanding  warrants, with an  exercise
price of $9.18 per share. To the extent these options or warrants are exercised,
there  will be further  dilution to the new  investors. Furthermore, the Company
has reserved 661,700 additional  shares of Common Stock  for issuance under  its
stock  plans.  The Company's  currently  outstanding shares  of  Series A  and B
Preferred Stock have antidilution and conversion adjustment provisions that will
increase or decrease  the number  of shares of  Common Stock  outstanding as  of
March  31, 1996, above or below the number  of shares used in the calculation of
dilution to new investors in the event that the initial public offering price is
less than or greater than $12.00 per share. See "Capitalization," "Management --
Stock Plans," "Description of  Capital Stock -- Preferred  Stock" and "--  Stock
Purchase Right and Warrants."
 
                                       19
<PAGE>
                            SELECTED FINANCIAL DATA
 
    The  following table sets forth selected  financial data of the Company. The
selected financial  data  for  each of  the  three  years in  the  period  ended
September  30, 1995 and the balance sheet data as of September 30, 1994 and 1995
are derived from the financial statements of the Company which have been audited
by Coopers & Lybrand L.L.P., independent accountants. The selected statements of
operations data for the period from May 8, 1992 (date of inception) to September
30, 1992, and  the balance sheet  data as of  September 30, 1992  and 1993,  are
derived  from audited financial statements not included herein. The statement of
operations data for the  six months ended  March 31, 1995 and  1996 and for  the
period  from May 8, 1992  (date of inception) to March  31, 1996 and the balance
sheet data as  of March  31, 1996, have  been derived  from unaudited  financial
statements  which include all adjustments, consisting solely of normal recurring
adjustments,  which  management  considers  necessary  to  fairly  present   the
financial  information set  forth herein. The  results for the  six months ended
March 31, 1995 and  1996, are not  necessarily indicative of  the results to  be
expected  for  future periods.  The selected  financial data  should be  read in
conjunction with "Management's  Discussion and Analysis  of Financial  Condition
and  Results  of  Operations" and  the  Financial Statements  and  related Notes
thereto and other financial information included elsewhere herein.
 
<TABLE>
<CAPTION>
                                                                                                              MAY 8, 1992
                                      MAY 8, 1992                                                               (DATE OF
                                       (DATE OF                                          SIX MONTHS ENDED      INCEPTION)
                                     INCEPTION) TO      YEARS ENDED SEPTEMBER 30,            MARCH 31,             TO
                                     SEPTEMBER 30,   --------------------------------  ---------------------   MARCH 31,
                                         1992          1993       1994        1995       1995        1996         1996
                                    ---------------  ---------  ---------  ----------  ---------  ----------  ------------
                                                            (IN THOUSANDS, EXCEPT PER SHARE DATA)
<S>                                 <C>              <C>        <C>        <C>         <C>        <C>         <C>
STATEMENT OF OPERATIONS DATA:
  Revenues........................     $      --     $      --  $      --  $    2,821  $       5  $      912   $    3,733
  Expenses:
    Research and development......           775         3,116      4,113       4,228      1,661       1,706       13,938
    General and administrative....           264         1,339      1,275       1,116        534         691        4,685
    Interest......................            23           246        648         352        304          56        1,325
                                         -------     ---------  ---------  ----------  ---------  ----------  ------------
      Total expenses..............         1,062         4,701      6,036       5,696      2,499       2,453       19,948
                                         -------     ---------  ---------  ----------  ---------  ----------  ------------
    Net loss......................     $  (1,062)    $  (4,701) $  (6,036) $   (2,875) $  (2,494) $   (1,541)  $  (16,215)
                                         -------     ---------  ---------  ----------  ---------  ----------  ------------
                                         -------     ---------  ---------  ----------  ---------  ----------  ------------
  Pro forma net loss per
   share (1)......................                                         $     (.63)            $     (.33)
                                                                           ----------             ----------
                                                                           ----------             ----------
  Pro forma weighted average
   shares outstanding (1).........                                          4,536,481              4,676,327
                                                                           ----------             ----------
                                                                           ----------             ----------
</TABLE>
 
<TABLE>
<CAPTION>
                                                                        SEPTEMBER 30,
                                                          ------------------------------------------
                                                            1992       1993       1994       1995     MARCH 31, 1996
                                                          ---------  ---------  ---------  ---------  --------------
                                                                                (IN THOUSANDS)
<S>                                                       <C>        <C>        <C>        <C>        <C>
BALANCE SHEET DATA:
  Cash and cash equivalents.............................  $      35  $      11  $      10  $   1,174    $       27
  Working capital.......................................       (379)      (497)      (988)      (269)         (800)
  Total assets..........................................        568         94        977      2,395         1,087
  Long-term obligations.................................      1,210      6,158     11,767        705         1,214
  Deficit accumulated during development stage..........     (1,062)    (5,763)   (11,799)   (14,674)      (16,215)
  Total stockholders' equity (deficit)..................     (1,057)    (5,755)   (11,791)      (101)       (1,291)
</TABLE>
 
- --------------------------
(1) See Note 1 of Notes to  Financial Statements for information concerning  the
    computation of pro forma net loss per share.
 
                                       20
<PAGE>
                      MANAGEMENT'S DISCUSSION AND ANALYSIS
                OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS
 
    THE  FOLLOWING  DISCUSSION AND  ANALYSIS OF  THE  RESULTS OF  OPERATIONS AND
FINANCIAL CONDITION  OF THE  COMPANY  SHOULD BE  READ  IN CONJUNCTION  WITH  THE
FINANCIAL STATEMENTS AND NOTES THERETO INCLUDED ELSEWHERE IN THIS PROSPECTUS.
 
OVERVIEW
 
    A  development stage company,  Progenitor was incorporated  in February 1992
and commenced operations in May 1992. The Company has devoted substantially  all
of  its resources since inception to research and development programs. To date,
all of the  Company's revenues  have resulted from  payments from  collaborative
partners  and a grant from the  U.S. Department of Commerce's National Institute
of Standards and Technology Advanced Technology Program ("ATP") that was awarded
to the Company in November  1994. Payments from collaborative partners,  license
fees, payments under governmental grants and investment income, in each case, if
any,  are expected to be the only sources of revenue for the foreseeable future.
Certain payments  under  collaborative  arrangements  are  contingent  upon  the
Company  meeting certain  milestones. Payments under  collaborative or licensing
arrangements, if any, will be subject to significant fluctuation in both  timing
and  amount and therefore the Company's results of operations for any period may
not be comparable to the results of operations for any other period. The Company
has not yet received any royalties or  other revenues from the sale of  products
or  services  and does  not expect  to receive  any such  revenues for  the next
several years,  if at  all.  As of  March  31, 1996,  the  Company had  a  total
stockholders' deficit of $1.3 million, including an accumulated deficit of $16.2
million.  See  "Risk Factors  -- History  of  Operating Losses;  Anticipation of
Future Losses."
 
    Interneuron provided the  initial funding  of the Company  and had  invested
$12.5  million in  Progenitor in  equity and  debt financings  through March 31,
1996. Interneuron  owns a  majority  of the  outstanding  capital stock  of  the
Company  and will own 51.2% (48.7% if the Underwriters' over-allotment option is
exercised in full) of the outstanding Common Stock following the closing of  the
Offering.  Interneuron has no  obligation to invest any  additional funds in the
Company, and the Company does not expect Interneuron to do so. Progenitor raised
an additional  $1.6 million  in  net proceeds  through  a private  placement  of
Preferred  Stock in fiscal 1995. The  Company intends to seek additional funding
through  public  or   private  equity  or   debt  financing  and   collaborative
arrangements. There can be no assurance, however, that additional financing will
be  available  when  needed,  or  that, if  available,  such  financing  will be
available on terms  acceptable to  the Company. See  "Risk Factors  -- Need  for
Additional Capital; Uncertainty of Additional Funding" and "Certain Transactions
- -- Relationship With Interneuron."
 
    Significant  discovery, research  and development  efforts will  be required
prior to the time any of the Company's gene, receptor or protein discoveries may
develop into product candidates or result in products that may be brought to the
market, if at all. Products, if  any, resulting from the Company's research  and
development  programs are not expected to be commercially available for a number
of years, if at all, even if any are successfully developed and proven safe  and
effective. Significant additional research and development efforts and extensive
preclinical  studies and clinical trials will be required prior to submission of
any regulatory application for commercial use. See "Risk Factors -- Early  Stage
of Development; Uncertainty of Final Product Development."
 
RESULT OF OPERATIONS
 
  SIX MONTHS ENDED MARCH 31, 1995 AND 1996
 
    Revenues  increased from $5,000 for  the six months ended  March 31, 1995 to
$912,000 for the six months ended March  31, 1996. The increase in revenues  was
attributable to a $500,000 payment received
 
                                       21
<PAGE>
in January 1996 from Chiron pursuant to the collaboration agreement entered into
in  March 1995, and  a payment of  $400,000 under the  Company's ATP grant which
provides for aggregate payments of $2.0 million over three years.
 
    Research and development expense was $1.7  million for the six months  ended
March  31,  1995 and  1996.  This expense  consisted  primarily of  salaries and
consulting fees,  sponsored research  projects and  expenditures for  laboratory
supplies  and animal  facilities. The  Company expects  research and development
expense to increase in  the future. Continued growth  in such expense,  however,
will be dependent on the availability of capital.
 
    General  and  administrative expense  increased  from $534,000  for  the six
months ended March 31, 1995 to $691,000 for the six months ended March 31, 1996.
The increase was largely due to increases in annual salaries, legal fees, travel
expenses and occupancy charges. The  Company expects general and  administrative
expenses  to  increase in  the future  as  it expands  its operations  and hires
additional employees.
 
    Interest expense decreased from $304,000 for the six months ended March  31,
1995 to $57,000 for the six months ended March 31, 1996. From its inception, the
Company  has incurred interest expense resulting  from the debt funding provided
by Interneuron. The decrease in interest expense for the six month period  ended
March  31,  1996  was  attributable  to  a  decrease  in  the  Company's average
outstanding borrowings, due  to the conversion  into equity in  January 1995  of
$11.5 million of the Company's debt payable to Interneuron.
 
  FISCAL YEARS ENDED SEPTEMBER 30, 1993, 1994 AND 1995
 
    The  Company  recognized  no  revenue  for  fiscal  1993  and  1994. Revenue
increased to $2.8 million in fiscal 1995. The Company's revenues in fiscal  1995
were attributable to an initial cash payment of $2.5 million under the Company's
collaboration  agreement  with Chiron  and  recognition of  $260,000  of revenue
related to a payment under the Company's ATP grant.
 
    Research and  development expense  increased from  $3.1 million  for  fiscal
1993,  to $4.1 million for fiscal 1994 and  to $4.2 million for fiscal 1995. The
increase in fiscal 1994 was largely due  to the addition of senior research  and
development  management in late fiscal 1993  as well as annual salary increases,
increased short-term sponsored research  commitments and increased  depreciation
expense  resulting from additions of  laboratory, office and computer equipment.
The increase in  research and  development expense  in fiscal  1995 was  largely
attributable to the incurrence of $750,000 as reimbursement for certain start-up
manufacturing costs related to the Chiron collaboration.
 
    General  and administrative  expense was  $1.3 million  for fiscal  1993 and
fiscal 1994, and decreased to $1.1 million for fiscal 1995. The slight  decrease
between  fiscal  1994  and  fiscal  1995  resulted  from  a  reimbursement  from
Interneuron of employee benefit expenses.
 
    Interest expense increased  from $245,000  for fiscal 1993  to $648,000  for
fiscal  1994 and decreased to $352,000 for fiscal 1995. The increase from fiscal
1993 to fiscal  1994 was due  to an  increase in the  Company's borrowings  from
Interneuron.  The decrease  in interest  expense in fiscal  1995 was  due to the
conversion into  equity  of $11.5  million  of  the Company's  debt  payable  to
Interneuron,  resulting  in a  lower average  debt balance  in fiscal  1995. The
Company began  incurring interest  expense related  to equipment  financings  in
fiscal  1994.  The Company  expects  to continue  financing  equipment purchases
through sale-leaseback  arrangements, if  favorable terms  are available,  which
could result in an increase in interest expense.
 
    No  income tax provision or benefit has been provided for federal income tax
purposes as the Company has incurred losses since inception. As of September 30,
1995,  the  Company  had  deferred  tax  assets  of  $5.7  million.  Because  of
uncertainties  surrounding the realization of  these favorable tax attributes in
future tax periods, all of the net deferred tax assets have been fully offset by
a valuation  allowance. As  of September  30, 1995,  the Company  had total  net
operating loss carryforwards of $13.1
 
                                       22
<PAGE>
million and tax credits of approximately $468,000, both of which expire on dates
through   2009.  The  Company's  ability  to  utilize  the  net  operating  loss
carryforwards in future years  may be limited  in some circumstances,  including
significant  changes in  ownership interests, due  to certain  provisions of the
Internal Revenue Code of 1986, as amended.
 
LIQUIDITY AND CAPITAL RESOURCES
 
   
    Since inception, Progenitor  has financed its  operations primarily  through
debt  and equity financings from Interneuron  of $12.5 million through March 31,
1996, a private  financing of  $1.6 million  in net  proceeds from  the sale  of
Preferred  Stock in fiscal 1995 and a private financing from The Ohio University
Foundation in February, 1996  of $350,000. In addition,  the Company received  a
$2.5 million payment from Chiron in April 1995 and received a payment of $65,000
in  August 1995 under  the ATP grant. The  Company also completed sale-leaseback
transactions generating $88,000  in cash  during fiscal 1995.  The Company  used
these  sources of financing to  fund its operations. During  fiscal 1995 and the
first six months of fiscal 1996, respectively, the Company used $1.6 million and
$2.0 million of cash in operating activities. As of March 31, 1996, the  Company
had cash and cash equivalents totaling $27,000.
    
 
    The  Company expects negative  cash flow from operations  to continue and to
increase for  the  foreseeable  future. The  Company  will  require  substantial
additional  funds  to  continue research  and  development,  conduct preclinical
studies and clinical trials, conduct activities relating to commercialization of
rights it has retained in strategic collaboration agreements, if any, and expand
administrative capabilities. The Company estimates that, at its planned rate  of
spending, its existing cash and cash equivalents, together with the net proceeds
from  the Offering and the  interest income thereon, will  be sufficient to meet
its capital  requirements for  at least  the next  18 months.  There can  be  no
assurance,  however, that the Company's  assumptions regarding its future levels
of expenditures and operating losses  will prove accurate. The Company's  future
capital  requirements  will depend  on  many factors,  including  the scientific
progress in and the breadth of the Company's research and development  programs;
the results of research and development, preclinical studies and clinical trials
conducted by the Company or its collaborative partners or licensees, if any; the
acquisition and licensing of products and technologies; the Company's ability to
establish  and maintain relationships with corporate and academic collaborators;
competing technological and market developments; the time and costs involved  in
filing,  prosecuting, defending  and enforcing patent  and intellectual property
claims; the receipt of  licensing or milestone fees  from any current or  future
collaborative   arrangements,   if   established;  the   continued   funding  of
governmental research grants; the  timing of regulatory  approvals, if any;  and
other  factors. To  the extent  undertaken by  the Company,  the time  and costs
involved  in  conducting  preclinical  studies  and  clinical  trials,   seeking
regulatory   approvals,  and  scaling-up   manufacturing  and  commercialization
activities also would  increase the  Company's capital needs.  The Company  will
need  to raise substantial additional capital  to fund operations. Prior to this
Offering, Interneuron has funded substantially all of the Company's  operations.
Interneuron,  however, is under  no obligation to provide,  and the Company does
not expect that Interneuron will provide, any additional funds in the future.
 
    The Company intends  to seek  additional funding through  public or  private
equity  or  debt  financing  and collaborative  arrangements.  There  can  be no
assurance that additional financing will be  available when needed, or that,  if
available,  such financing will be available on terms acceptable to the Company.
If additional  funds  are  raised  by issuing  equity  securities,  dilution  to
existing  stockholders will  result. In addition,  in the  event that additional
funds are  obtained  through  arrangements  with  collaborative  partners,  such
arrangements  may require  the Company  to relinquish  rights to  certain of its
technologies or potential products  that it would otherwise  seek to develop  or
commercialize  itself. If funding is insufficient at any time in the future, the
Company may be required  to delay, scale  back or eliminate some  or all of  its
research and development programs or cease operations. See "Risk Factors -- Need
for Additional Capital; Uncertainty of Additional Funding."
 
                                       23
<PAGE>
                                    BUSINESS
 
    Progenitor  is  a  functional  genomics company  engaged  in  the discovery,
characterization and validation of novel  genes, receptors and related  proteins
as  therapeutic  leads and  targets  for the  treatment  of major  diseases. The
Company's functional genomics approach combines developmental biology  expertise
and  proprietary  technology with  gene sequencing  and other  molecular biology
techniques to accelerate the discovery process. Using its developmental  biology
approach  to  functional genomics,  the  Company has  made  several discoveries,
including the discovery of the B219  leptin receptor, for which it filed  patent
applications in September and December 1994. Leptin is believed to have roles in
blood  cell formation  ("hematopoiesis"), reproduction and  obesity. The Company
has entered  into a  collaboration with  Chiron Corporation  ("Chiron") for  the
development  and  commercialization  of  the  Company's  proprietary  T7T7  gene
delivery system, and a collaboration with Novo Nordisk A/S ("Novo Nordisk")  for
the isolation, development and commercialization of blood cell growth factors.
 
BACKGROUND
 
    Genes  play an important role in the structure and function of an organism's
cells and therefore provide a fundamental basis for understanding the causes of,
and potentially developing treatments for, many human diseases. Genes consist of
discrete sequences of DNA that are  comprised of unique orderings of  nucleotide
base  pairs. These  genetic sequences provide  instructions to the  cell for the
synthesis of proteins through a process  known as gene expression. Proteins  are
responsible  for the structure and biological functions of all organisms through
their regulation of, and participation in, cell structure, growth and  activity,
as  well as  their involvement in  communications and  interactions among cells.
Cells often communicate through  receptor-mediated interactions using a  protein
or  other ligand  that binds  specifically to  a cell-surface  protein receptor.
These receptor-mediated communications  are fundamental  to the  differentiation
and organization of cells during the early development of an organism.
 
    Although  most cells  contain an  organism's entire  genome, or  full set of
genes, only a small fraction of an organism's genome is expressed in each  cell.
The genes expressed, as well as the order, level and timing of their expression,
determine  the function of different cells within an organism. Intrinsic defects
in genes, or defects  caused by external stimuli,  may lead to inappropriate  or
inadequate  production of proteins,  resulting in abnormal  or degenerative cell
functions  that  characterize  various  diseases  such  as  cancer.   Therefore,
determining  the role of specific genes, receptors and related proteins involved
in cell  functions may  provide a  basis for  understanding the  causes of,  and
developing possible treatments for, these diseases.
 
  OVERVIEW OF DEVELOPMENTAL BIOLOGY
 
    Developmental  biology is the study of  the genetic and cellular events that
control the  transformation of  a  single fertilized  egg into  a  fully-formed,
complex organism. This transformation is orchestrated by the interactive up- and
down-regulation  of gene expression by a small fraction of the organism's genes.
The expression of these  regulatory genes results in  the synthesis of  proteins
that  regulate the expression of other  genes and control cell functions, direct
cell to  cell communications  and  affect development  of cells  throughout  the
embryo.  Many genes involved  in the process of  cell growth and differentiation
may be expressed exclusively,  or at enhanced levels,  during certain stages  of
early  development and may  become inactive in the  normal cells of fully-formed
organisms. The Company believes that the discovery and characterization of genes
involved in early  development, and the  proteins they produce,  may be used  to
develop treatments for a range of diseases characterized by aberrant cell growth
or differentiation.
 
    Developmental  biology seeks to  define the process  and mechanisms by which
non-committed, immature cells (stem cells) differentiate into specialized  cells
performing specific functions. For example, the blood and immune systems develop
from  a  few precursor  stem cells  that grow  in  the yolk  sac, a  tissue that
surrounds the developing embryo. In early  stages of development, each of  these
yolk sac stem cells
 
                                       24
<PAGE>
is  capable of developing into any of the mature cells of the blood. However, as
development progresses, individual  cells differentiate into  specific types  of
blood  and immune cells as a result of patterns of specific gene expression. The
yolk sac also  is the source  of the earliest  endothelial cell precursors  that
grow  and differentiate to form blood vessels. These endothelial cell precursors
also express proteins that  direct the growth and  differentiation of the  blood
cells.  The following diagram illustrates the development of a single fertilized
egg into a seven-day-old mouse embryo.
 
   
    [Diagram showing  five  stages  in  the development  of  an  embryo  from  a
fertilized  egg cell to the blastula  stage (fertilized egg cell, cleavage, four
cells, sixteen cells  and blastula), above  the caption "Embryonic  Development"
and  a drawing of a seven-day-old mouse embryo with its yolk sac and three types
of mature cells that develop from the yolk sac.]
    
 
  OVERVIEW OF GENOMICS
 
    Recent developments in  the study  of the genome  (genomics), including  the
introduction  and  improvement  of  automated equipment,  have  allowed  for the
identification  of  genes  that  may  contribute  to  or  inhibit  abnormal   or
degenerative  cell activity common  to certain diseases.  Genomics may therefore
represent a  useful  first  step toward  discovering  and  developing  effective
diagnostic processes and therapies to detect and treat these diseases.
 
    Traditional  genomics companies may be  divided broadly into those employing
high-volume gene sequencing techniques and  those engaged in gene mapping.  Gene
sequencing  companies use high-throughput equipment to identify randomly the DNA
sequences of a large number of genes, generally without any initial reference to
their biological  function. Individual  gene sequences  then are  selected  from
among  these randomly generated sequences by using screening techniques based on
the similarity  of  the  selected  sequence to  sequences  within  known  genes.
Selected  genes then are  subjected to an  extensive series of  assays to define
their biological function  and determine  their potential  therapeutic role,  if
any.  High-throughput gene  sequencing as a  primary means of  gene discovery is
capital intensive, requires extensive effort to sift through the large volume of
identified  sequences,  and  produces  a  relatively  low  yield  of   potential
therapeutic targets.
 
                                       25
<PAGE>
    Gene  mapping companies analyze the differences between genetic sequences of
well-defined  healthy   and   diseased  populations   of   genetically   related
individuals,  in order to  identify and sequence  genes that may  play a role in
specific diseases.  Gene mapping  is  a labor  intensive,  technically-demanding
process  that typically  seeks to identify  a single  disease-related gene. This
approach often is even more complex  for diseases involving multiple genes.  The
success   of  this  approach  depends  upon  identifying  a  sufficiently  large
population  of  related  individuals  with  strong  evidence  of  a  genetically
transmitted  disease. As a  result, the use  of this approach  may be limited to
those diseases where  discrete populations of  genetically related, healthy  and
diseased individuals are readily accessible.
 
PROGENITOR'S FUNCTIONAL GENOMICS APPROACH
 
    Progenitor  uses developmental biology  as a discovery  platform to identify
novel genes,  receptors  and  related  proteins that  control  cell  growth  and
differentiation  through which the blood, immune, vascular and other systems are
developed. By comparing  the sequential expression  of genes from  one stage  of
early development to the next, the Company believes it can identify, isolate and
sequence  specific genes, receptors  and related proteins  which play functional
roles in this process.  The Company believes that  its approach provides a  rich
and  largely unexploited source  for the discovery  of medically important leads
and targets to develop  treatments for diseases  characterized by aberrant  cell
growth  or  differentiation. These  diseases  include cancer,  blood  and immune
system disorders and degenerative diseases associated with aging.
 
    Progenitor's approach starts with  the identification of medically  relevant
biological  functions that  are involved  in the  differentiation of early-stage
stem cells, tissues, and systems derived from various murine embryonic  sources,
including  yolk sac stem  cells and embryonic stem  ("ES") cells. Progenitor has
isolated proprietary cell  lines from these  murine sources, which  it uses  for
analyzing  relevant biological  functions, such  as the  normal establishment of
organ systems.  The Company  then develops  and applies  proprietary assays  and
model  systems to further characterize a selected biological function. Following
function characterization, the Company uses gene sequencing and other  molecular
biology techniques to identify the genes, receptors or other proteins associated
with  that function.  The Company  also uses a  wide variety  of other classical
developmental  and  molecular  biology  techniques,  including  enhancer  traps,
promoter  traps, IN SITU hybridization, subtractive cloning, gene knock-outs and
transgenic methods to supplement its proprietary capabilities. These  techniques
allow  the Company  to correlate gene  expression with  biological function. The
Company then  screens for  biological  activity in  adult  tissues in  order  to
validate  the potential  of isolated  genes, receptors  and related  proteins as
therapeutic leads  and  targets. The  Company  believes that  its  developmental
biology  approach  to  functional  genomics  will  permit  more  accelerated and
cost-effective discoveries of  therapeutically relevant  drug development  leads
and targets than traditional genomics approaches.
 
    The  Company conducts its initial research  in murine systems because murine
cells and tissues  are accessible and  can be manipulated  in ways not  feasible
with humans cells and tissues. In addition, the genetic composition and patterns
of  gene expression in murine cells are highly similar to those in humans. These
similarities enable the Company  first to identify  and isolate relevant  murine
genes,  receptors or  proteins and then  to identify the  equivalent human gene,
receptor or protein without the need for complex and time-consuming assays using
human cells  and  tissues.  See  "Risk  Factors  --  Uncertainties  Relating  to
Technological Approach of the Company."
 
PROGENITOR'S PROPRIETARY DISCOVERY TECHNOLOGIES
    The  Company possesses a number of key proprietary technologies that it uses
in its discovery  programs. The  Company seeks protection  of these  proprietary
technologies   through  maintenance  of  trade  secrets  and  by  filing  patent
applications,  where  appropriate.  Progenitor's  key  proprietary  technologies
relate  to ES cells, yolk sac stem cells, discovery techniques for hematopoietic
growth factors and  receptors and  gene delivery  systems. See  "-- Patents  and
Proprietary Rights."
 
                                       26
<PAGE>
  EMBRYONIC STEM CELL TECHNOLOGY
 
    The Company has developed proprietary methods and cell lines using murine ES
cells  for  studying  cell differentiation  in  the development  of  tissues and
organs. The Company maintains murine ES cells in culture in an  undifferentiated
state and then modifies the culture conditions to control the progression of the
ES  cells from one stage  of development to the  next. Using this technique, the
Company is able  to control and  time the cell  differentiation process and  can
accurately isolate and modify cells from the earliest stages of the formation of
the  blood, immune,  vascular and other  systems. These  capabilities enable the
Company to take  multiple "molecular snapshots"  in order to  isolate the  genes
associated with these critical developmental stages.
 
    These  methods  and cell  lines also  serve  as assay  systems in  which the
expression of discovered  genes can  be manipulated  in order  to clarify  their
function  further. The ES cells can be  manipulated in order to study the effect
of the  addition  or  deletion of  specific  genes  on normal  cell  growth  and
differentiation, either IN VITRO or IN VIVO. The Company currently is using this
technology to identify the genes, receptors and related proteins involved in the
development of the blood and vascular systems, and to develop assays for cloning
the  murine burst-forming units-erythroid ("BFU-e") red blood cell growth factor
and its human equivalent.
 
  YOLK SAC STEM CELL TECHNOLOGY
 
    Progenitor has developed proprietary  techniques to isolate, grow,  maintain
in  culture and differentiate cells isolated from  the murine yolk sac. Yolk sac
stem cells  appear later  in development  than ES  cells, and  are committed  to
develop  only into cells of the blood,  immune and vascular systems. The Company
believes the mammalian  yolk sac to  be one of  a number of  tissues that is  an
enriched  source of novel genes that may be expressed exclusively or at enhanced
levels during early development.
 
    Progenitor has used cultured yolk sac stem cell lines to identify its murine
BFU-e red blood  cell growth factor  activity. The Company  is using these  cell
lines  in its program to isolate the factor  and clone its gene, and to identify
other  genes,  receptors  and   related  proteins  with  potential   therapeutic
applications.  The Company has a pending patent application relating to cellular
compositions derived from the  mammalian yolk sac and  methods of obtaining  and
using  such  compositions.  See  "Risk Factors  --  Uncertainty  of  Patents and
Proprietary Rights."
 
  TECHNOLOGY FOR DISCOVERY OF NOVEL RECEPTORS
 
    Progenitor has developed proprietary  gene cloning and screening  techniques
to  identify novel members of a family of genes that encode receptors for growth
factors involved in normal blood cell formation ("hematopoiesis") as well as  in
the growth and development of neural and other tissues. The Company's techniques
rely   on  enhancements   to  traditional  cloning   techniques,  including  the
development of  proprietary screening  algorithms  used in  the selection  of  a
targeted  family of genes. The Company applies its receptor discovery techniques
to enriched  gene sources  produced through  a combination  of proprietary  cell
lines,   freshly  isolated   cell  subpopulations,   and  proprietary   ES  cell
differentiation methods.  The Company  used these  methods to  discover  certain
leptin  receptors (including various isoforms of the leptin receptor), for which
it filed U.S.  patent applications  in September and  December 1994.  Progenitor
intends  to  use its  discovered receptors  to identify  and clone  novel growth
factors, to  screen  for  small  molecules that  activate  or  inhibit  receptor
functions, and to identify and purify unique bone marrow cells.
 
  T7T7 GENE DELIVERY SYSTEM
 
   
    The  Company,  in  collaboration  with  Ohio  University,  has  developed  a
proprietary nonviral gene delivery  system known as  T7T7. The Company  believes
that the T7T7 gene delivery system may enable it
    
 
                                       27
<PAGE>
   
to  express  genes in  cells  in order  to  facilitate the  characterization and
validation of  its discoveries.  The  Company believes  that its  gene  delivery
system,  in addition to other  gene delivery techniques, may  allow it to assess
efficiently the biological effects of discovered genes while saving the time and
expense of  producing and  characterizing quantities  of purified  protein  that
would otherwise be required for these studies.
    
 
    The  T7T7 system is a nonviral, naked DNA plasmid that can effect expression
of the gene it carries in the cytoplasm of a cell and works IN VIVO and IN VITRO
in both dividing and  nondividing cells. In contrast,  most other gene  delivery
systems  must  reach the  cell  nucleus to  be  effective and  function  only in
dividing cells.
 
    The Company has filed  a U.S. patent  application and corresponding  foreign
applications relating to the T7T7 gene delivery system. In March 1996, the USPTO
issued  a notice of allowance on the  patent application for claims covering the
composition of  matter  and methods  for  using  the T7T7  system.  The  Company
currently  is working with Chiron to  explore potential commercialization of the
T7T7 system  in clinical  gene therapy  applications. The  Company has  licensed
certain   technologies  incorporated   in  the   T7T7  system   from  Associated
Universities, Inc.  and  the Wisconsin  Alumni  Research Foundation.  See  "Risk
Factors -- Uncertainty of Patents and Proprietary Rights."
 
PROGENITOR'S DISCOVERY PROGRAMS
 
    The  Company, using  its proprietary cell  lines and  technologies, has made
three principal  discoveries  to date.  These  discoveries and  their  potential
therapeutic applications are described below.
 
  LEPTIN RECEPTORS
 
   
    The  Company has utilized  its proprietary receptor  discovery technology to
identify gene  sequences  that  encode  various  isoforms  of  the  B219  leptin
receptor.  Leptin receptors recently  have been implicated  in the regulation of
obesity and the control of appetite and metabolic activity. However, in a recent
publication of NATURE MEDICINE, the  Company disclosed findings suggesting  that
leptin  receptors may play  a broader and more  fundamental biological role than
has been  recognized previously.  The  Company has  demonstrated IN  VITRO  that
leptin,  acting on a leptin receptor,  stimulates the growth and differentiation
of certain hematopoietic cells, including cells  found in adult bone marrow.  In
addition,  the Company demonstrated IN VIVO  that leptin receptors are expressed
in ovarian  cells  critical  for  controlling  the  growth  and  development  of
reproductive cells, and that leptin is found in high levels in the ovarian fluid
surrounding  the reproductive  cells. Progenitor  believes that  these receptors
could provide  a  means  to  identify novel  proteins,  or  ligands,  and  other
molecules that have unique and important therapeutic and diagnostic applications
in  hematopoiesis,  reproduction  and  obesity.  In  addition,  leptin receptors
potentially may be used to sort  immature blood cells and create  subpopulations
of cells expressing a desired receptor for use as therapeutic leads. In order to
characterize   further  the  function  of   leptin  receptors,  the  Company  is
researching the  role of  the leptin  protein in  the hematopoietic  and  immune
systems,  as well  as its  role in  the growth  and development  of reproductive
cells. The Company intends to establish strategic corporate partnerships for the
development and  commercialization of  its leptin  receptors. In  September  and
December  1994, the Company filed U.S.  patent applications relating to the B219
leptin receptor (including varous isoforms of the leptin receptor). There can be
no assurance that patents will issue  from these applications, that, if  issued,
any  resulting patents  will provide the  Company with  meaningful protection or
rights, that  the Company  will  be successful  in entering  into  collaborative
agreements   or  that  any  drugs  or   other  products  will  be  developed  or
commercialized from the Company's leptin receptor discoveries. See "Risk Factors
- -- Early Stage of  Development; Uncertainty of  Final Product Development,"  "--
Dependence on Collaborators," "-- Uncertainty of Patents and Proprietary Rights"
and "-- Dependence upon Research Collaborators and Scientific Advisors."
    
 
                                       28
<PAGE>
  DEL-1 GENE
 
    Progenitor  has discovered, in collaboration  with Vanderbilt, DEL-1, a gene
that encodes  a novel  cell-surface protein  involved in  the early  growth  and
development  of  blood  vessels  and  bone.  The  growth  of  new  blood vessels
(angiogenesis) is an important activity in development that is typically  absent
in  normal adult tissues, but may be present in certain disorders such as cancer
and diabetic retinopathy. Progenitor  and Vanderbilt have  shown that the  DEL-1
gene  is expressed uniquely in areas of developing blood vessels and bone but is
inactive in normal, mature animal  systems. Moreover, Progenitor has shown  that
mice  implanted with  human tumors express  the murine DEL-1  gene in developing
blood vessels that feed the tumor.
 
    The Company believes that targeting the protein expressed by the DEL-1  gene
(Del-1)  to inhibit the growth  of new blood vessels  may represent an important
new therapeutic  approach to  treating cancer.  The rapidly  dividing  malignant
cells of a tumor require a large, continuous and ever-increasing blood supply. A
substantial  body of research in animals  and humans suggests that attacking the
growth of tumor blood  vessels may be an  effective treatment for cancer.  Since
the  DEL-1 gene is normally not expressed in the adult, and the Del-1 protein is
accessible in  the lining  of  blood vessels,  the  Company believes  the  Del-1
protein  may  be  a  highly  specific,  accessible  and  stable  target  for the
development of cancer therapeutics, diagnostics and imaging agents. Other  genes
identified to date that are involved in the regulation of blood vessel formation
are  also expressed in  normal adult tissues  and thus may  not provide the same
potential selectivity as the Del-1 protein as a target for cancer detection  and
therapy.
 
    The  Company intends to enter into  academic and corporate collaborations to
pursue the research, development and commercialization of the DEL-1 gene and the
Del-1 protein for  the treatment  of diseases characterized  by excessive  blood
vessel  formation, such as cancer, and diseases such as cardiovascular and other
disorders that may be treated by stimulating blood vessel growth.
 
   
    Progenitor and Vanderbilt have  fully sequenced the  human and murine  DEL-1
genes,  respectively.  Progenitor and  Vanderbilt  have filed  two  joint patent
applications relating  to  the DEL-1  nucleotide  sequences, the  proteins  they
encode, methods of expressing functional gene products, and methods of using the
DEL-1  gene  and protein  and  engineered cells  in  various normal  and disease
conditions. The  Company has  an exclusive,  worldwide license  to  Vanderbilt's
commercial  rights under  these patent applications.  There can  be no assurance
that patents will issue from these applications, that, if issued, any  resulting
patents  will provide the Company with meaningful protection or rights, that the
Company will be successful in entering into collaborative agreements or that any
drugs or products will be developed  or commercialized from the Company's  DEL-1
discoveries.  See "Risk  Factors -- Early  Stage of  Development; Uncertainty of
Final Product Development," "-- Dependence on Collaborators," "-- Uncertainty of
Patents and Proprietary Rights" and "-- Dependence on Research Collaborators and
Scientific Advisors."
    
 
  BFU-E RED BLOOD CELL GROWTH FACTOR
 
    Progenitor has identified from its murine yolk sac stem cell lines a  growth
factor activity that stimulates the formation and development of red blood cells
from  the BFU-e red blood cell precursors, which are found in adult bone marrow.
The identified  activity is  distinct from  that of  erythropoietin ("EPO")  and
other known growth factors. The Company is attempting to purify the BFU-e growth
factor and clone its gene.
 
    The  Company believes there  is a large  and growing market  for agents that
stimulate new blood cell development. These include support therapy for patients
with inherited anemias, or patients  who are undergoing kidney dialysis,  cancer
chemotherapy or bone marrow transplantation. In order to address these potential
markets, Progenitor has entered into an agreement with Novo Nordisk, through its
subsidiary,   ZymoGenetics,   Inc.  ("ZymoGenetics"),   for  the   research  and
development relating  to  the  BFU-e  red  blood  cell  growth  factor  activity
identified  by the Company.  Progenitor, along with Novo  Nordisk, is seeking to
clone the murine BFU-e  red blood cell growth  factor and its human  equivalent.
There  can be  no assurance  that the  Company will  be successful  in cloning a
murine BFU-e red blood cell
 
                                       29
<PAGE>
   
growth  factor or validating its significance as a therapeutic lead or that Novo
Nordisk will be successful in developing  or commercializing any drugs or  other
products  based on the BFU-e red blood  cell growth factor. To date, the Company
has not  filed any  patent applications  relating to  the BFU-e  red blood  cell
growth  factor  activity.  See  "Risk Factors  --  Early  Stage  of Development;
Uncertainty of Final Product Development," "-- Dependence on Collaborators," "--
Uncertainty of Patents and  Proprietary Rights" and  "-- Dependence on  Research
Collaborators and Scientific Advisors."
    
 
  OTHER PROGRAMS
 
    GENE  THERAPY.  The Company believes that the T7T7 gene delivery system will
enable it to deliver genes to cells IN VIVO and IN VITRO in order to  facilitate
the characterization and validation of its discoveries. In addition, the Company
has  entered into a collaborative agreement with Chiron to explore clinical uses
of the Company's  T7T7 gene delivery  system. Under this  agreement, Chiron  has
agreed  to develop and potentially to commercialize the T7T7 system for selected
applications. Progenitor has retained the right  to market and license the  T7T7
system  for other applications and to use  and license joint technologies of the
collaboration as well as technological improvements  to the T7T7 system made  by
Chiron. The initial T7T7-based gene therapy product being developed by Chiron is
intended  for treatment  of solid-tumor cancers.  The Company  intends to pursue
opportunities with other corporate partners to develop gene therapies using  the
T7T7   system  for  applications  retained  by  Progenitor.  See  "--  Strategic
Collaboration Agreements -- Chiron Agreement" and "Risk Factors -- Dependence on
Collaborators."
 
   
    NOVEL RECEPTORS.    The  Company continues  to  apply  discovery  techniques
similar  to  those  used in  its  early  discovery of  certain  leptin receptors
(including various  isoforms  of  the  leptin receptor)  in  order  to  identify
additional novel gene sequences and receptors. These techniques have resulted in
the  identification  of over  30 additional  novel  genes that  are structurally
similar to members of the hematopoietin receptor gene family. While the  Company
has  not fully  characterized the  discovered genes,  it believes  that they may
represent potential  targets  for  discovering  additional  growth  factors  and
isolating  important cell subpopulations for  therapeutic approaches to diseases
characterized by aberrant cell growth or differentiation.
    
 
STRATEGY
 
    The Company's strategy includes the following elements:
 
    EMPLOY  DEVELOPMENTAL  BIOLOGY   APPROACH.    The   Company  is  using   its
developmental biology approach to functional genomics in order to accelerate the
discovery,   characterization  and  validation  of  medically  important  genes,
receptors and related  proteins as drug  development leads and  targets for  the
pharmaceutical  industry. The Company intends to enhance its technology platform
and supplement  its  internal  research  and  development  capabilities  through
further  academic collaborations.  In order  to increase  the efficiency  of the
discovery process once a targeted  biological function has been identified,  the
Company  also  intends  to  acquire additional  advanced  molecular  biology and
genomics equipment and capabilities, including high-throughput gene  sequencing,
bio-informatics, robotic cloning, biological assays and protein analysis.
 
    ENTER  INTO STRATEGIC  ALLIANCES FOR  PRODUCT DEVELOPMENT.   The  Company is
focusing its  resources on  the discovery,  characterization and  validation  of
novel  genes, receptors and  related proteins that  may play key  roles in major
diseases. The  Company  intends  to  enter  into  strategic  alliances  for  the
development  and  commercialization of  drugs and  other  products based  on its
discoveries. This strategy  is intended to  enable the Company  to maximize  the
effectiveness  of  its  discovery  technologies and  to  use  its collaborators'
expertise and resources in research and development, clinical testing, obtaining
regulatory approvals, and manufacturing and marketing. The Company believes this
strategy will allow it  to benefit from  the development of  any drugs or  other
products    that   may   result   from   its   discoveries   without   incurring
 
                                       30
<PAGE>
the substantial costs associated with such development. The Company has  entered
into  an agreement with Chiron for the development of gene therapies for certain
cancers using the Company's T7T7 gene delivery system, and with Novo Nordisk for
the isolation and development of a BFU-e growth factor.
 
    PURSUE PATENT PROTECTION.  The Company  will continue to seek protection  of
its  discoveries  and  proprietary  technologies  through  maintenance  of trade
secrets  and  by  filing  patent  applications,  where  appropriate.  There   is
substantial   uncertainty  regarding  the  strength  of  patents  for  partially
sequenced genes or for genes without a known function. The Company believes that
its functional genomics approach improves the Company's ability to identify  and
correlate gene sequences with known biological functions and thereby may enhance
the  likelihood of ultimately securing patent  protection for its discoveries of
novel genes, receptors and related proteins and their uses.
 
STRATEGIC COLLABORATION AGREEMENTS
 
  CHIRON AGREEMENT
 
    In March 1995,  Progenitor entered  into an  agreement with  Chiron for  the
development and commercialization of the Company's T7T7 gene delivery system for
selected  applications.  The  agreement grants  Chiron  an  exclusive, worldwide
license to  the  T7T7 gene  delivery  system for  (i)  all products  carrying  a
specified  gene, which has potential applications  for tumor ablation; (ii) four
infectious disease vaccine constructs; (iii)  products used for the  prevention,
therapy  or  diagnosis  of  human restenosis;  (iv)  five  additional constructs
designated by Chiron; and (v)  additional constructs, with certain  limitations,
that  may be designated by Chiron upon payment of a fee for each such additional
construct. Progenitor also may grant licenses to third parties to constructs for
fields of use not licensed  to and not in  conflict with the exclusive  licenses
granted  to Chiron. Any such third-party  licenses are subject to Chiron's right
of first refusal for any construct of the T7T7 gene delivery system not  already
covered by the agreement for the development of a noninfectious disease vaccine.
Pursuant  to the agreement, Chiron and  Progenitor will develop jointly the T7T7
tumor ablation product for the treatment of cancer. The parties will own jointly
all preclinical and clinical data from  the collaboration, which may be used  by
either  party  for any  purpose  subject to  the  exclusive licenses  granted to
Chiron. Progenitor has the right to  collaborate and jointly invest in  Chiron's
development   efforts  on  the  tumor   ablation  product,  with  the  Company's
participation in  any resulting  product revenues  based on  its  contributions.
Under  the  agreement,  Chiron  has  committed  to  use  reasonable  efforts  to
commercialize one or more licensed products and has certain manufacturing rights
and obligations  for  any  resulting  products. If  Chiron  chooses  to  abandon
development  of a construct,  its license rights terminate  with respect to that
construct. Subject to  the foregoing  rights, the agreement  provides that  each
party  will retain  ownership of all  inventions (and any  related patents) made
solely by its  employees and  arising from  the activities  performed under  the
agreement.
 
    The  agreement terminates  upon the later  of the expiration  of the patents
upon which it is based or, within  any given country, ten years after the  first
commercial  sale of a product developed under the agreement within such country.
In  such  events,  Chiron's  affected  license  rights  become  fully-paid   and
non-exclusive.  Chiron may also terminate the  agreement earlier with respect to
any particular construct upon  30 days' notice, and  either party may  terminate
the  agreement in  the event  of a  material breach  by the  other party  of its
obligations under the agreement. In  such events, Chiron's license rights  would
revert to Progenitor, but Chiron would retain exclusive rights to inventions and
discoveries  made solely by its employees,  and joint rights to discoveries made
jointly with Progenitor.  Chiron also would  be required to  pay Progenitor  all
royalties accrued before termination.
 
    Progenitor  received a $2.5 million payment  upon execution of the agreement
as a license fee  and reimbursement of past  research and development  expenses,
and an additional $500,000 in January 1996 for continued funding of Progenitor's
research  and development expenses. Progenitor has paid Chiron $750,000 pursuant
to the agreement, in full  satisfaction of Progenitor's obligation to  reimburse
Chiron for certain start-up manufacturing costs. Under the agreement, Progenitor
is entitled to receive up to an
 
                                       31
<PAGE>
additional $4.3 million in various fees and milestone payments for each licensed
product   if  all  specified  research,  clinical  development,  regulatory  and
marketing approval milestones are achieved, plus additional fees for development
of specific  constructs  and for  the  first product  developed.  The  agreement
encompasses  a minimum of eleven potential  products that Chiron may develop. In
the event that all  such milestones are achieved  and all contemplated  products
reach  market, Progenitor would receive an aggregate of $51.3 million (including
payments already received) plus royalties on net product sales. There can be  no
assurance  that  the Company  and  Chiron will  be  successful in  developing or
commercializing any drugs or products utilizing Progenitor's T7T7 gene  delivery
system  or that such  agreement will not  terminate prior to  its expiration. As
such, there can be no assurance that any milestones will be achieved or that any
royalties or other payments contemplated by the agreement will ever be made. See
"Risk Factors -- Dependence on Collaborators."
 
  NOVO NORDISK AGREEMENT
 
    In  May  1995,   Progenitor  and  Novo   Nordisk,  through  its   subsidiary
ZymoGenetics,   entered  into  a  research,  development  and  commercialization
agreement under which Novo Nordisk  received an exclusive, worldwide license  to
any  and all rights  of the Company related  to the BFU-e  red blood cell growth
factor activity  identified  by  the  Company  for use  in  any  and  all  human
therapeutic  and  small  molecule drug  design  uses. Under  the  agreement, the
development effort  is divided  into  two stages.  During  the first  stage,  if
commenced,  Novo Nordisk will attempt to purify,  clone and sequence a BFU-e red
blood cell growth  factor and  other growth factors  with similar  hematopoietic
functions.  If this stage is successfully  completed, Novo Nordisk will have the
right to decide whether to proceed to the second stage, in which Progenitor will
conduct research  to establish  the biological  function of  the growth  factor.
During  the second stage, if commenced, Progenitor may be entitled to receive up
to $4.0 million in research fees from Novo Nordisk.
 
   
    The agreement with Novo Nordisk terminates  upon the expiration of the  last
patent related to the Company's growth factor discoveries. Novo Nordisk also has
a  right to earlier termination  of the agreement upon  30 days' notice. If Novo
Nordisk exercises this right before payment  of any license fees required  under
the  agreement,  it  would be  obligated  to  grant to  Progenitor  an exclusive
worldwide license to  all of  Novo Nordisk's  rights arising  from the  research
conducted  pursuant to the agreement to make,  use and sell related products. In
the event  that Novo  Nordisk had  paid the  Company at  least $4.0  million  in
research  fees under the  agreement prior to  such early termination, Progenitor
would be obligated to pay Novo Nordisk royalties for any sales of products  made
using the licensed technology.
    
 
   
    If  Novo  Nordisk  decides to  develop  any  licensed products,  it  will be
obligated to pay Progenitor a one-time license fee of $5.0 million and up to  an
additional   $18.0  million  for  each  product  if  certain  clinical  testing,
regulatory and marketing approval  milestones are met,  plus an additional  $1.0
million  for  milestones related  to the  first  licensed product.  In addition,
Progenitor has the right  to royalties for sales  of any resulting products.  In
the  event that all milestones  are reached with respect  to the BFU-e red blood
cell growth factor, Progenitor would receive an aggregate of $28.0 million under
the agreement, plus royalties on net  product sales. Novo Nordisk has the  right
to  manufacture and  market any such  products on an  exclusive worldwide basis.
There can be  no assurance that  the Company or  Novo Nordisk will  successfully
clone the murine BFU-e red blood cell growth factor or its human equivalent, or,
if cloned, that Novo Nordisk will continue the program, that the Company will be
able  to establish  the biological  function of the  growth factor  or that Novo
Nordisk will be successful in developing and commercializing any drugs or  other
products utilizing the BFU-e red blood cell growth factor. As such, there can be
no  assurance that  any milestones  will be achieved,  or that  any royalties or
other payments  contemplated by  the  agreement will  ever  be made.  See  "Risk
Factors -- Dependence on Collaborators."
    
 
                                       32
<PAGE>
LICENSE AGREEMENTS
 
  OHIO UNIVERSITY
 
    Progenitor   entered  into  research  and  licensing  agreements  with  Ohio
University as of January 1992  relating to yolk sac stem  cells and as of  April
1993  relating to  the T7T7  gene delivery  system. The  agreements, as amended,
grant Progenitor an exclusive worldwide license  to the yolk sac stem cells  and
T7T7  gene delivery  system, respectively,  and related  technologies covered in
Ohio University's  existing patents  and  patent applications,  as well  as  any
technology  developed  from its  related  sponsored research.  In  exchange, the
Company is  obligated  to pay  certain  license and  research  fees as  well  as
royalties  based on net sales of any  resulting products. In addition, under the
1992 license agreement and the terms of a related stock purchase agreement,  The
Ohio  University Foundation received a 5% equity interest in the Company subject
to certain antidilution protection and was granted the right to purchase  25,000
shares  of Progenitor's Common Stock in the event of an initial public offering,
merger or other similar corporate  transactions at a price  equal to 50% of  the
anticipated   public  offering  price  or  merger  or  other  consideration,  as
applicable. The Ohio University Foundation has agreed to exercise such right  in
full prior to the closing of the Offering. Under the license agreement, The Ohio
University  Foundation has  the right  to designate  two representatives  to the
Board of Directors of Progenitor until Progenitor consummates an initial  public
offering. See "Certain Transactions -- The Ohio University Foundation."
 
  VANDERBILT UNIVERSITY
 
    In  July 1995, Progenitor  entered into a  license agreement with Vanderbilt
pursuant  to  which  Progenitor  obtained  an  exclusive  worldwide  license  to
Vanderbilt's  commercial  rights under  a jointly  owned patent  application, to
develop and market products and  processes utilizing technology relating to  the
DEL-1  gene. The gene was co-discovered by Progenitor and Vanderbilt. Under this
agreement, Progenitor is  obligated to  pay royalties on  any resulting  product
sales.  Vanderbilt University may  terminate the agreement  after three years if
Progenitor has not made adequate efforts to commercialize products based on  the
gene.
 
ADVANCED TECHNOLOGY PROGRAM GRANT
 
    In  November 1994, the Company was  awarded a $2.0 million, three-year grant
to study the  immunology of yolk-sac-derived  endothelial cells for  therapeutic
applications  under the  ATP. The grant  specifies the  research and development
therapeutics based  on  an  understanding  of  the  biology  of  development  of
endothelial   cells.  The  research  agreements  between  the  Company  and  its
subcontractors under the ATP grant  (the University of Colorado, The  University
of  Wisconsin,  Ohio University,  Vanderbilt University  and Bio  Support, Inc.)
require that all parties assign rights to any inventions made by them under  the
grant  to the  Company. The  ATP grant  provides that  the Company  retains full
rights to any intellectual property developed as part of the project.
 
   
    The ATP grant is administered by United States Department of Commerce. As of
May 31, 1996, the  Company had received  $646,000 under the  ATP grant, and  had
accrued  $129,000 in  additional funds  payable to  the Company  through May 31,
1996. Under the  terms of  the grant,  the Company  is scheduled  to receive  an
aggregate  of $702,000  payable in equal  quarterly installments  for the period
from June 1, 1996 through May 31,  1997. The balance of the grant, $518,000,  is
payable  in equal quarterly installments during the  period from June 1, 1997 to
May 31, 1998. The grant is subject to yearly appropriations by the United States
Congress for the ATP program, and  legislation has been introduced to  eliminate
the program. The National Institute of Standards and Technology has informed the
Company that, although it could not comment on the availability of funds for the
Company's  grant for the year ending May 31, 1998, there are sufficient funds in
the  ATP  grant  program's  current   budget  to  support  grant  payments   for
    
 
                                       33
<PAGE>
   
currently  funded grants for the year ending May 31, 1997, and that therefore it
is likely that Progenitor will receive  grant payments expected through May  31,
1997.  There can be no assurance, however, that funding for the ATP program will
not be reduced or eliminated at any time.
    
 
PATENTS AND PROPRIETARY RIGHTS
 
    Patents  and  licenses  are  important  to  the  Company's  businesses.  The
Company's   policy  is  to  file  patent  applications  to  protect  technology,
inventions and improvements to inventions  that are considered important to  the
development of its business. The Company also relies on trade secrets, know-how,
continuing  technological innovations and licensing opportunities to develop and
maintain its competitive position. To date, the Company has filed or exclusively
licensed a number of  pending patent applications in  the USPTO relating to  its
various  core technology programs, as well as foreign counterparts of certain of
these applications in Europe, Japan  and certain other countries. These  pending
patent  applications include  the following:  six U.S.  applications relating to
leptin receptors (including various isoforms  of the leptin receptor); two  U.S.
applications  relating  to  its  vascular  biology  program  (DEL-1);  one  U.S.
application  relating  to  its  gene  delivery  system  (T7T7);  and  one   U.S.
application  relating to yolk sac stem cells. No United States or foreign patent
has issued to the Company to date. However, the Company has an exclusive license
from Ohio University to  one issued U.S. patent  covering a method of  providing
tissue-specific  expression  of  exogenous  genetic  material  in  a  mammal  by
genetically transformed embryonic carrier cells such as yolk sac cells. A notice
of allowance has been  received for the patent  application with respect to  the
Company's  T7T7 gene delivery  system. The Company  has exclusive licenses under
the patent  application relating  to the  T7T7 gene  delivery system  from  Ohio
University,  the patent  application relating to  yolk sac stem  cells from Ohio
University, and  the  patent  applications  relating  to  the  DEL-1  gene  from
Vanderbilt  University. The  Company has also  licensed two  issued patents that
relate to its T7T7 gene delivery program on a nonexclusive basis from Associated
Universities, Inc. and the Wisconsin Alumni Research Foundation.
 
    The Company's success will depend to a significant extent on its ability  to
obtain and enforce patents, maintain trade secret protection and operate without
infringing  on  the  proprietary rights  of  third parties.  Because  the patent
positions of biotechnology and pharmaceutical companies can be highly  uncertain
and  frequently  involve complex  legal and  factual  questions, the  breadth of
claims  allowed   in  biotechnology   and   pharmaceutical  patents   or   their
enforceability cannot be predicted. Commercialization of pharmaceutical products
can  be  subject to  substantial delays  as a  result of  the time  required for
product development, testing and regulatory  approval. The value of any  patents
issued  or licensed to the Company may  depend upon the remaining term of patent
protection available at the time  products that utilize the patented  technology
are commercialized.
 
    The  Company actively  pursues a policy  of seeking patent  protection for a
number of its  proprietary products  and technologies.  Progenitor has  licensed
from  Ohio  University  one U.S.  patent  and pending  U.S.  patent applications
relating to  stem cell  technology  and to  gene  delivery technology  (and  has
received   a  notice  of  allowance  relating  to  a  gene  delivery  technology
application), along with certain  corresponding foreign patent applications  and
one issued foreign patent. Progenitor has filed six patent applications relating
to  certain  leptin receptors,  including  applications filed  in  September and
December 1994.  In March  1996,  Progenitor's international  patent  application
covering certain leptin receptors was published. The Company believes that there
may  be significant litigation regarding  patent and other intellectual property
rights relating  to leptin  and  leptin receptors.  The  Company is  aware  that
Millennium  has filed a patent application relating to a receptor for leptin and
its use in  obesity applications,  and has  licensed to  Hoffmann-La Roche  Inc.
rights  to develop certain therapeutics for obesity using Millennium's discovery
of a leptin receptor.
 
   
    Millennium has recently filed  a "Protest" in the  USPTO in connection  with
the   Progenitor  applications  relating  to  leptin  receptors,  including  the
applications filed in  September and December  1994. A Protest  is an  available
procedure  sometimes used by a third party to provide the patent examiner who is
reviewing the involved  application or  applications with what  the third  party
believes to be relevant
    
 
                                       34
<PAGE>
   
information.  The Protest procedure does not afford any right to the third party
to participate  in the  patent  prosecution process  beyond  the filing  of  its
written  Protest. Millennium's Protest primarily  argues that any claims allowed
to Progenitor  should  not be  so  broad as  to  cover Millennium's  own  leptin
receptor.  Progenitor  intends to  proceed with  the  prosecution of  its leptin
receptor patent  applications  in the  normal  course  in order  to  obtain  the
broadest allowable claims with regard to its leptin receptor discoveries.
    
 
   
    There   can  be  no  assurance  that  Millennium's  patent  application,  or
additional patent applications filed by Millennium or others, will not result in
issued patents covering a leptin receptor, the leptin protein or other  ligands,
or  any of their  respective uses including  obesity. There can  be no assurance
that the invention by Millennium will  be accorded an invention date later  than
Progenitor's  invention date, that  any patent will issue  to Progenitor or that
any such  patent issued  to Progenitor  would be  broad enough  to cover  leptin
receptors  of Millennium or others. Progenitor's failure to obtain a patent on a
leptin receptor,  or its  failure to  obtain  a patent  that covers  the  leptin
receptors  of Millennium or others, or the issuance of a patent to a third party
covering a leptin receptor, the leptin protein or other ligands, or any of their
respective uses, could have a material adverse effect on the Company's business,
financial condition and results of operations.
    
 
    A number of other groups are  attempting to identify partial gene  sequences
and  full-length genes, the functions of  which have not been characterized. The
public availability  of partial  gene sequence  information before  the  Company
applies  for  patent  protection  on  a  corresponding  full-length  gene  could
adversely affect the Company's ability to obtain patent protection with  respect
to  such gene. To the extent any patents  issue to other parties on such partial
or full-length  genes, and  as other  patents issue  with the  expansion of  the
biotechnology  industry,  the risk  increases  that the  potential  products and
processes of the Company or its  collaborative partners may give rise to  claims
of patent infringement.
 
    The  patent positions  of pharmaceutical and  biotechnology firms, including
the Company, are uncertain and involve  complex legal and factual questions  for
which  important legal principles are largely unresolved, particularly in regard
to human therapeutic  uses. Substantial periods  of time pass  before the  USPTO
responds  to patent applications. In addition,  the coverage claimed in a patent
application  can  be   significantly  reduced   before  a   patent  is   issued.
Consequently,  the Company does  not know whether  any of its  pending or future
patent applications will result  in the issuance of  patents or, if any  patents
are  issued,  whether  the  patents will  be  subjected  to  further proceedings
limiting their  scope, and  whether they  will provide  significant  proprietary
protection  or competitive  advantage, or  will be  circumvented or invalidated.
Because patent applications in the United States are maintained in secrecy until
patents issue and patent applications  in certain other countries generally  are
not  published  until  more than  18  months  after they  are  filed,  and since
publication of discoveries in scientific or patent literature often lags  behind
actual  discoveries, the Company cannot  be certain that it  or any licensor was
the first creator of inventions covered  by pending patent applications or  that
it  or  such  licensor  was  the  first  to  file  patent  applications  on such
inventions.
 
    There can be no  assurance that the Company's  patents, if issued, would  be
held  valid or enforceable by a court  or that such patents would cover products
or  technologies  of  the   Company's  competitors.  Competitors  or   potential
competitors  may have filed applications for or received patents, and may obtain
additional patents and  proprietary rights  relating to  compounds or  processes
competitive  with those of  the Company. To protect  its proprietary rights, the
Company may be required to  participate in interference proceedings declared  by
the  USPTO to determine priority of invention, which could result in substantial
cost to the Company. Moreover, even if the Company's patents issue, there can be
no assurance that they  will provide sufficient  proprietary protection or  will
not  be later limited, circumvented or invalidated. Accordingly, there can be no
assurance that  the  Company  will develop  proprietary  technologies  that  are
patentable,  that the Company's patent applications will result in patents being
issued or that, if  issued, patents will  afford protection against  competitors
with  similar technology or  products, nor can  there be any  assurance that the
Company's patents will be held valid by a court of competent jurisdiction.
 
                                       35
<PAGE>
    In addition to patent protection, the  Company also relies to a  significant
extent  upon  trade  secret  protection  for  its  unpatented  confidential  and
proprietary  information  including   many  of  the   Company's  key   discovery
technologies,  such  as its  proprietary methods  of isolating  and manipulating
murine ES cells. There  can be no assurance  that others will not  independently
develop  substantially  equivalent  proprietary  information  and  techniques or
otherwise  gain  access  to  the  Company's  trade  secrets  or  disclose   such
technology.  To protect its  trade secrets, the  Company requires its employees,
consultants, scientific  advisors and  parties  to collaborative  agreements  to
execute  confidentiality  agreements upon  the  commencement of  employment, the
consulting relationship or the  collaboration with the Company.  In the case  of
employees,  the agreements also provide that  all inventions resulting from work
performed by them while employed by  the Company will be the exclusive  property
of  the Company. There can be no  assurance, however, that these agreements will
provide meaningful  protection  of  the  Company's  trade  secrets  or  adequate
remedies  in the  event of unauthorized  use or disclosure  of such information,
that the  Company  can  meaningfully  protect  its  rights  in  such  unpatented
proprietary  technology through other means, that any obligation to maintain the
confidentiality  of  such  proprietary  technology  will  not  be  breached   by
employees,  consultants,  advisors, collaborative  partners  or others,  or that
others will not independently  develop substantially equivalent technology.  The
loss  of  trade  secret  protection  of  any  of  the  Company's  key  discovery
technologies would  materially and  adversely affect  the Company's  competitive
position  and could  have a material  adverse effect on  the Company's business,
financial condition and results of operations. Finally, disputes may arise as to
the ownership of proprietary rights to the extent that outside collaborators  or
consultants  apply technological information developed  independently by them or
others to Company projects or apply Company technology to other projects and, if
adversely determined, such disputes could have a material adverse effect on  the
Company's business, financial condition and results of operations.
 
    The  Company may incur substantial costs if  it is required to defend itself
in patent suits brought by third parties or if the Company initiates such a suit
to enforce the Company's patents or to determine the scope and validity of other
parties' proprietary  rights.  Any  legal  action against  the  Company  or  its
collaborators  or licensees  claiming damages  and seeking  to enjoin commercial
activities relating to the affected products and processes could, in addition to
subjecting the Company to potential  liability for damages, require the  Company
or  its collaborators or licensees  to obtain a license  or licenses in order to
continue to manufacture or market the affected products and processes. There can
be no assurance that the Company or its collaborators or licensees would prevail
in any such action or that any license required under any such patents would  be
made  available on commercially acceptable terms, if at all. Any adverse outcome
of such  litigation  could have  a  material  adverse effect  on  the  Company's
business,  financial position  and results  of operations.  In addition,  if the
Company becomes  involved in  such litigation,  it could  consume a  substantial
portion  of the  Company's managerial  and financial  resources. The  Company is
unable to predict  how courts  will resolve any  future issues  relating to  the
validity and scope of its patents should they be challenged.
 
    It  is uncertain whether any third-party patents will require the Company to
alter its products or  processes, obtain licenses,  cease certain activities  or
pay substantial damages. If any licenses are required, there can be no assurance
that  the  Company will  be  able to  obtain  any such  license  on commercially
acceptable terms, if  at all. Failure  by the Company  or its collaborators  and
licensees  to obtain a  license to any technology  required to commercialize the
Company's discoveries  may  have a  material  adverse effect  on  the  Company's
business,  financial condition and  results of operations.  See "Risk Factors --
Uncertainty of Patents and Proprietary Rights."
 
COMPETITION
 
    Research in the field of genomics is highly competitive. Competitors of  the
Company  in the  genomics area include,  among others, public  companies such as
Genome  Therapeutics   Corporation,   Human  Genome   Sciences,   Inc.,   Incyte
Pharmaceuticals,   Inc.,   Millennium,   Myriad  Genetics,   Inc.   and  Sequana
Therapeutics, Inc.,  as  well  as private  companies  and  major  pharmaceutical
companies and
 
                                       36
<PAGE>
universities  and other research institutions, including those receiving funding
from the  federally  funded Human  Genome  Project.  A number  of  entities  are
attempting  to  rapidly identify  and patent  randomly-sequenced genes  and gene
fragments.  In   addition,  certain   other  entities   are  pursuing   a   gene
identification,  characterization and product development strategy based on gene
mapping.  The  Company's  competitors  may  discover,  characterize  or  develop
important  genes in advance of the Company,  which could have a material adverse
effect on any related Company discovery program. The Company expects competition
to intensify in genomics  research as technical advances  in the field are  made
and become more widely known.
 
    In  addition,  the  Company  faces,  and  will  continue  to  face,  intense
competition from pharmaceutical and biotechnology companies, as well as academic
and research institutions and governmental  agencies. The Company is subject  to
significant competition from organizations that are pursuing the same or similar
technologies  as those  which constitute  the Company's  discovery platform, and
from organizations that are pursuing pharmaceutical or diagnostic products  that
are  competitive with  the Company's  or its  collaborators' potential products.
Many of  the  organizations competing  with  the Company  have  greater  capital
resources,  larger  research  and  development  staffs  and  facilities, greater
experience in drug discovery and development, obtaining regulatory approvals and
pharmaceutical product manufacturing,  and greater  marketing capabilities  than
the Company.
 
    The Company also is aware of a number of companies and institutions that are
developing or considering the development of potential gene-based and cell-based
treatments,  including early-stage gene  therapy companies, large pharmaceutical
companies, academic  and research  institutions, government  agencies and  other
health care providers. Many of these entities are more advanced than the Company
in their product development programs for gene and cell-based therapies and have
more  experience with regulatory agencies and clinical trials. The field of gene
and cell-based therapy is new and many competitive approaches are being taken to
discover practical means by which these technologies can be made into  products.
Rapid  technologic  advances could  result in  actual or  proposed technologies,
products or  processes of  the  Company becoming  obsolete prior  to  successful
commercialization. See "Risk Factors -- Intense Competition; Rapid Technological
Change."
 
    The  Company is and  will continue to  be reliant on  strategic partners for
support  of  its  programs,  including  preclinical  and  clinical  development,
manufacturing  and  marketing of  its initial  products.  Each of  the Company's
present and future partners is  conducting multiple product development  efforts
within  each disease or technology area that is the subject of the alliance with
the Company. Any product candidate or technology of the Company, therefore,  may
be subject to internal competition with a potential product under development or
technology  platform under evaluation by a  strategic partner. See "Risk Factors
- -- Dependence on Collaborators."
 
GOVERNMENT REGULATION
 
    Prior to marketing, any new drug  or other product developed by the  Company
and  its collaborative  partners must  undergo an  extensive regulatory approval
process in the United States and other countries. This regulatory process, which
includes preclinical studies and clinical trials, and may include post-marketing
studies, of each product candidate to establish its safety and efficacy, usually
takes  many  years  and  require  the  expenditure  of  substantial   resources.
Preclinical tests include laboratory evaluations and will require animal studies
conducted  in  accordance the  FDA's cGLP  regulations  to assess  the product's
potential safety  and  efficacy.  Data obtained  from  preclinical  studies  and
clinical  trials are  susceptible to  varying interpretations  that could delay,
limit  or  prevent  regulatory  approval.  Delays  or  rejections  also  may  be
encountered  based  upon changes  in  the FDA's  policies  for drug  or biologic
approval during the period of product  development and FDA regulatory review  of
each  NDA submitted in the case of new pharmaceutical agents, or PLA in the case
of biologics. Product  development of new  pharmaceuticals is highly  uncertain,
and  unanticipated  developments,  clinical  or  regulatory  delays,  unexpected
adverse side effects or  inadequate therapeutic efficacy  could slow or  prevent
the  product  development  efforts  of  the  Company  and  its  collaborators or
licensees,  and   have   a   materially  adverse   effect   on   the   Company's
 
                                       37
<PAGE>
business,  financial  condition  and  results of  operations.  There  can  be no
assurance that  regulatory approval  will be  obtained for  any drugs  or  other
products  developed by the  Company or its  collaborative partners or licensees.
Furthermore, regulatory approval may entail limitations on the indicated use  of
a  drug or other product. Because certain  of the products likely to result from
the Company's discovery programs involve the application of new technologies and
may be based upon a  new therapeutic approach, such  products may be subject  to
substantial additional review by various government regulatory authorities other
than  the FDA and, as a result, regulatory approvals may be obtained more slowly
than for  products using  conventional technologies.  Under current  guidelines,
proposals  to conduct clinical  research involving gene  therapy at institutions
supported by the NIH must be approved by the RAC and the NIH. Furthermore,  gene
therapies  are relatively new technologies and  have not been tested extensively
in humans.  The regulatory  requirements governing  these products  and  related
clinical procedures for their use are uncertain and are subject to change.
 
    Even  if  regulatory  approval  is  obtained,  a  marketed  product  and its
manufacturer are subject to continuing review. Among the conditions for  product
approval  and  continued  marketing approval  is  that the  quality  control and
manufacturing procedures of the Company or its collaborative partners conform to
the FDA's cGMP  regulations which must  be followed at  all times. In  complying
with  cGMP requirements, manufacturers  must expend time, money  and effort on a
continuing  basis   in  production,   record   keeping  and   quality   control.
Manufacturing   establishments,  both  domestic  and  foreign,  are  subject  to
inspection by or under the authority of the FDA and by other federal, state  and
local agencies. Failure to pass such inspections may subject the manufacturer to
possible  FDA actions  such as the  suspension of manufacturing,  seizure of the
product, withdrawal of approval or other regulatory sanctions. The FDA also  may
require the manufacturer to recall a product from the market.
 
    Discovery  of previously  unknown problems with  a product  may have adverse
effects on the Company's business, including withdrawal of the product from  the
market.   Violations  of   regulatory  requirements  at   any  stage,  including
preclinical studies and clinical trials, the approval process or  post-approval,
may  result in various adverse consequences  to the Company, including the FDA's
delay in approval  or refusal to  approve a product,  withdrawal of an  approved
product  from the  market or  the imposition  of criminal  penalties against the
manufacturer and NDA or PLA holder. The Company has not submitted an IND for any
product  candidate,   and   no  product   candidate   has  been   approved   for
commercialization in the United States or elsewhere. The Company intends to rely
primarily  on  its strategic  partners  to file  INDs  and generally  direct the
regulatory approval process. No assurance can  be given that the Company or  any
of its strategic partners will be able to conduct clinical testing or obtain the
necessary  approvals  from  the  FDA or  other  regulatory  authorities  for any
products. Failure  to  obtain  required governmental  approvals  will  delay  or
preclude the Company's strategic partners from marketing drugs or other products
developed  by the Company or limit the commercial use of such products and could
have a material adverse  effect on the  Company's business, financial  condition
and results of operations.
 
    In  addition to regulations enforced by the FDA, the Company also is subject
to regulation under the  Occupational Safety and  Health Act, the  Environmental
Protection  Act, the Toxic Substances Control Act, the Resource Conservation and
Recovery Act  and other  federal,  state and  local regulations.  The  Company's
research  and  development activities  involve the  controlled use  of hazardous
materials, chemicals, biological materials  and radioactive compounds.  Although
the  Company believes that  its safety procedures for  handling and disposing of
such materials comply with the current standards prescribed by state and federal
laws and regulations, the risk of accidental contamination or injury from  these
materials cannot be completely eliminated. In the event of such an accident, the
Company  could be held liable  for any resulting damages  and any such liability
could  exceed  the  Company's  resources.   See  "Risk  Factors  --   Government
Regulation" and "-- Hazardous and Radioactive Materials; Environmental Matters."
 
                                       38
<PAGE>
PRODUCT LIABILITY INSURANCE
 
    The  testing, manufacture,  marketing and  sale of  pharmaceutical and other
products entail the  inherent risk of  liability claims or  product recalls  and
associated  adverse publicity. Clinical  trials and sales by  the Company or its
collaborators or  licensees of  potential products  incorporating the  Company's
discoveries may expose the Company to potential liability resulting from the use
of  such  products. Such  liability might  result from  claims made  directly by
consumers or by regulatory agencies, pharmaceutical companies or others  selling
such  products. The Company currently has a limited amount of clinical trial and
product liability insurance coverage through Interneuron. The Company will  seek
to  obtain its own coverage upon completion of this Offering and to maintain and
appropriately increase  such coverage  as clinical  development of  any  product
candidates   progresses  and  if   and  when  its  products   are  ready  to  be
commercialized. There  can be  no assurance  that the  Company will  be able  to
obtain  such insurance or, if obtained, that such insurance can be acquired at a
reasonable cost or  in sufficient amounts  to protect the  Company against  such
liability.  Certain of the  Company's license agreements  require the Company to
indemnify licensors  against  product  liability claims  arising  from  products
developed  using the licensed technology. Also,  certain of these agreements and
other collaboration agreements require the Company to maintain minimum levels of
insurance coverage. The failure to  maintain product liability coverage, or  the
occurrence  of any product liability  claim, or a recall  of any products of the
Company or  its  collaborators or  licensees,  if developed,  could  inhibit  or
prevent  commercialization of products being developed  by the Company and could
have a material adverse  effect on the  Company's business, financial  condition
and  results of  operations. In  addition, to  the extent  any product liability
claim exceeds  the amount  of any  insurance coverage,  the Company's  business,
financial  condition and results of operations could be materially and adversely
affected. See "Risk Factors -- Risk of Product Liability."
 
HUMAN RESOURCES
 
    As of May 1, 1996,  Progenitor had 24 full-time  employees, of whom 11  hold
Ph.D.  or M.D. degrees. Of the Company's  full-time employees, 19 are engaged in
research  and  development   activities  and  five   are  engaged  in   business
development,  finance  and administration.  None of  the Company's  employees is
covered by  a  collective  bargaining  agreement,  and  the  Company  has  never
experienced any strike or work stoppage. The Company believes its relations with
its employees to be good.
 
    In  order to support the Company's  existing operations, it will be required
to  hire  and  retain   additional  management,  administrative  and   financial
personnel,  including  a chief  financial  officer. The  Company's  success will
depend in large  part on its  ability to  attract and retain  key employees  and
scientific  advisors.  Competition  among biotechnology  and  pharmaceutical and
other companies  for  highly  skilled scientific  and  management  personnel  is
intense.  There  can be  no assurance  that  the Company  will be  successful in
retaining its  existing  personnel  or advisors,  or  in  attracting  additional
qualified  employees.  See "Risk  Factors --  Dependence on  Collaborators," "--
Dependence on Research Collaborators and Scientific Advisors" and "-- Dependence
on Key Personnel."
 
FACILITIES
 
    Progenitor currently occupies approximately 19,000 square feet of laboratory
and office space in  a single facility in  Columbus, Ohio. Total lease  payments
for  fiscal  1995 were  $106,970.  In addition,  the  Company leases  a separate
facility with  approximately 7,000  square feet  of space  from The  Ohio  State
University for laboratory animals. Space in this facility is leased on the basis
of  a  per  diem  for each  animal  housed.  Total payments  to  The  Ohio State
University in fiscal 1995 were $23,582. The current lease on the laboratory  and
office  facility expires  on December  31, 1996  and includes  an option  for an
additional  one-year  extension.  Although  the  Company  believes  that   these
facilities  will be adequate to meet its projected needs for the next two years,
it may be required  to locate additional or  alternative facilities within  this
time frame, depending on the Company's growth and development.
 
                                       39
<PAGE>
                                   MANAGEMENT
 
DIRECTORS AND EXECUTIVE OFFICERS
 
    The current executive officers and directors of the Company are as follows:
 
   
<TABLE>
<CAPTION>
                    NAME                           AGE                                POSITION
- ---------------------------------------------      ---      ------------------------------------------------------------
<S>                                            <C>          <C>
Douglass B. Given, M.D., Ph.D................          44   President, Chief Executive Officer and Director
H. Ralph Snodgrass, Ph.D.....................          46   Vice President, Research and Chief Scientific Officer
Stephen J. Williams, Ph.D....................          42   Vice President, Corporate Development
Glenn L. Cooper, M.D.........................          43   Chairman of the Board
Robert P. Axline.............................          60   Director
Alexander. M. Haig, Jr.......................          71   Director
Morris Laster, M.D...........................          32   Director
Jerry P. Peppers.............................          50   Director
David B. Sharrock............................          60   Director
</TABLE>
    
 
    DOUGLASS  B. GIVEN,  M.D., PH.D.  has served  as President,  Chief Executive
Officer and Director of the Company since June 1994 and served as Executive Vice
President and Chief Operating Officer from  January 1993 to June 1994. Prior  to
joining Progenitor, Dr. Given was Vice President at the Schering Plough Research
Institute, a pharmaceutical research facility, from March 1989 to December 1992.
Dr.  Given also serves as  a Director of the  Edison BioTechnology Center, is on
the Dean's Advisory Council of  the University of Chicago  and is on the  Dean's
Advisory  Council of The Ohio  State University. Dr. Given  received an M.D. and
Ph.D. in  Biological Sciences  from  the University  of Chicago,  performed  his
post-doctoral  training in Internal Medicine  and Infectious Diseases at Harvard
Medical School and Massachusetts  General Hospital and  received an M.B.A.  from
the Wharton School of Business at the University of Pennsylvania.
 
    H.  RALPH SNODGRASS, PH.D. has served  as Chief Scientific Officer since May
1996 and has served as Vice President,  Research since he joined the Company  in
July 1993. Prior to joining Progenitor, Dr. Snodgrass was Assistant Professor of
Microbiology  and Immunology  at the University  of North  Carolina, Chapel Hill
from January 1988 to June 1993. Dr. Snodgrass has held appointments at The  Ohio
State  University  as  Clinical  Associate Professor,  Division  of  Bone Marrow
Transplantation, Department of Internal Medicine since July 1994, and as Adjunct
Associate Professor,  Department of  Medical Microbiology  and Immunology  since
July 1995. Dr. Snodgrass received his Ph.D. in Immunology from the University of
Pennsylvania  and performed his  post-doctoral training at  The Fox Chase Cancer
Center, Philadelphia.
 
    STEPHEN  J.  WILLIAMS,  PH.D.  has  served  as  Vice  President,   Corporate
Development  since May  1996 and previously  served as  Vice President, Business
Development from  June  1994 to  May  1996.  Prior to  joining  Progenitor,  Dr.
Williams  was  Medical  Director, Strategic  Product  Planning  at Bristol-Myers
Squibb from  March  1993 to  June  1994;  and Associate  Director,  New  Product
Planning at DuPont Merck Pharmaceutical Company from January 1991 to March 1993.
Dr. Williams received his Ph.D. in Pharmacology from Duke University.
 
    GLENN  L. COOPER, M.D. has  served as Chairman of  the Board of Directors of
the Company since June 1994,  and has been a  director since December 1992.  Dr.
Cooper has been President, Chief Executive Officer and a director of Interneuron
since May 1993 and served as President and Chief Executive Officer of Progenitor
from  September 1992 until June  1994. Prior to joining  Progenitor in 1992, Dr.
Cooper was  Executive  Vice President  and  Chief Operating  Officer  of  Sphinx
Pharmaceuticals  Corporation from August 1990. Dr.  Cooper serves as Chairman of
the Boards of Directors of  Intercardia, Inc. and Transcell Technologies,  Inc.,
and  is  a director  of  InterNutria, Inc.,  each of  which  is a  subsidiary of
Interneuron.
 
                                       40
<PAGE>
Dr. Cooper  received his  M.D.  from Tufts  University  School of  Medicine  and
performed  his  post-doctoral  training  in  Internal  Medicine  and  Infectious
Diseases at  the  New  England  Deaconess  Hospital  and  Massachusetts  General
Hospital.
 
    ROBERT  P. AXLINE  has been a  Director of  Progenitor since June  1992 as a
designee of The  Ohio University Foundation.  Mr. Axline has  been President  of
Image  Data Systems Inc.  since 1995 and  Chairman of Plastic  Card Systems Inc.
since 1987. Both companies  are engaged in the  manufacture and sale of  plastic
identification card machines and supplies.
 
    ALEXANDER  M. HAIG,  JR. has  been a  Director of  Progenitor since December
1992. General Haig has served as Chairman and President of Worldwide Associates,
Inc., a marketing consulting firm,  since 1984. Previously, General Haig  served
as  Secretary of State of the United States  from January 1981 to July 1982, and
President and Chief  Operating Officer of  United Technologies Corporation  from
November  1979 to  January 1981, where  he remains a  Senior Consultant. General
Haig has also served as Supreme Allied  Commander of NATO and White House  Chief
of  Staff under the Nixon and Ford  Administrations. General Haig also serves on
the Board of Directors of Interneuron, MGM Grand, Inc. and America Online, Inc.
 
    MORRIS LASTER,  M.D.  has served  as  a  Director of  Progenitor  since  its
inception  and served as Chief Executive Officer from its inception to September
1992. Dr.  Laster  has been  Vice  President of  The  Castle Group,  Ltd.  since
February  1990. He has also served as Chief Executive Officer of Synpro, Ltd., a
biotechnology firm,  since  November  1995. Previously,  he  was  interim  Chief
Executive  Officer of  Xenograft Technologies, Ltd.,  a biopharmaceuticals firm,
from January 1993 to September 1993. Dr. Laster received his M.D. from Downstate
Medical Center, New York, and received post-doctoral training in surgery at Case
Western Reserve University Hospital.
 
    JERRY P. PEPPERS joined  Progenitor's Board of Directors  in June 1992 as  a
designee  of The Ohio University Foundation. He is  a partner in the law firm of
Winthrop, Stimson, Putnam &  Roberts, where he has  served as an attorney  since
1971. Mr. Peppers received his J.D. from Duke University.
 
    DAVID B. SHARROCK has been a Director of Progenitor since January 1994 and a
Director  of Interneuron  since January 1995.  Mr. Sharrock  has been associated
with Marion Merrell Dow,  a pharmaceuticals company,  or its predecessors  since
1958,  most recently as Executive Vice President and Chief Operating Officer and
Director from January  1990 until his  retirement in December  1993. Since  that
time  he has served as an independent  consultant. Mr. Sharrock also serves as a
Director of Cincinnati Bell Inc., Unitog Company, Inc. and Intercardia, Inc.
 
BOARD OF DIRECTORS COMMITTEES AND OTHER INFORMATION
 
    At present, all  directors are  elected annually  and serve  until the  next
meeting  of  stockholders  or  until the  election  and  qualification  of their
successors. In addition, The Ohio University Foundation is entitled to designate
two directors. Messrs. Axline  and Peppers currently serve  as the designees  of
The  Ohio University Foundation. The rights of The Ohio University Foundation to
designate two members of the Board of Directors will terminate upon the  closing
of the Offering. See "Certain Transactions -- The Ohio University Foundation."
 
   
    The  Board  of  Directors intends  to  establish  an Audit  Committee  and a
Compensation Committee prior to the closing of the Offering. The Audit Committee
will oversee the actions  by the Company's independent  auditors and review  the
Company's   internal  financial  and  accounting   controls  and  policies.  The
Compensation Committee will be responsible for determining salaries,  incentives
and  other forms of compensation for officers and other employees of the Company
and will administer various incentive compensation and benefit plans.
    
 
                                       41
<PAGE>
    All executive officers serve  at the discretion of  the Board of  Directors,
subject to the terms of any employment agreements. Currently, the Company has an
employment  agreement only  with Dr.  Given. There  are no  family relationships
among the  Company's  directors  and  executive  officers.  See  "--  Employment
Agreement."
 
DIRECTORS' COMPENSATION
 
    Except  as described below, the Company's directors do not currently receive
any cash compensation  for service on  the Board of  Directors or any  committee
thereof, but directors may be reimbursed for certain expenses in connection with
attendance at Board of Directors and committee meetings. Prior to the closing of
the  Offering, the Company intends to establish  a formal policy relating to the
compensation of directors.
 
    Pursuant to a letter agreement dated January 26, 1994, the Company pays  Mr.
Sharrock $2,000 for each meeting of the Board that he attends. Upon execution of
this  agreement, the Company also granted Mr. Sharrock options to purchase 2,500
shares of Common Stock, at  an exercise price of  $4.00 per share, one-third  of
which  vest each January 21 beginning January  21, 1995. During fiscal 1995, the
Company paid Mr.  Sharrock $6,000 pursuant  to this arrangement  and accrued  an
additional $2,000 in fees.
 
   
    The  Company,  along with  Interneuron and  Transcell Technologies,  Inc., a
subsidiary of Interneuron ("Transcell"),  is a party  to a consulting  agreement
with  Mr. Sharrock,  entered into  on February  1, 1994,  pursuant to  which Mr.
Sharrock receives $2,000 per day in exchange for his service as a consultant  on
the   development   and   commercialization   of   each   company's  technology.
Collectively, the three companies must use Mr. Sharrock's services for a minimum
of 20 days  per year  during the  term of the  agreement. The  Company paid  Mr.
Sharrock  $4,000  during  fiscal  1995  under  this  arrangement.  The agreement
provides that Mr. Sharrock will not compete with the Company during the term  of
the agreement and for a period of one year thereafter. This agreement terminates
on  February 1,  1997, with automatic  one-year extensions with  respect to each
company unless Mr.  Sharrock or such  company gives notice  at least sixty  days
prior to expiration of the then-current term.
    
 
    During fiscal 1995, the Company was party to a consulting agreement with Dr.
Laster,  pursuant to which the Company paid  him $500 per month for his services
as a scientific advisor. Dr. Laster  received $7,000 pursuant to this  agreement
in fiscal 1995, including $1,000 in fees accrued but not paid in fiscal 1994.
 
                                       42
<PAGE>
EXECUTIVE COMPENSATION
 
    The  following table sets forth for the fiscal year ended September 30, 1995
the compensation for  services rendered to  the Company in  all capacities  with
respect  to its Chief Executive Officer and each of its other executive officers
with annual compensation in excess of $100,000 (the Chief Executive Officer  and
such  other  executive  officers  are  hereinafter  referred  to  as  the "Named
Executive Officers"):
 
                           SUMMARY COMPENSATION TABLE
 
   
<TABLE>
<CAPTION>
                                                                                       LONG-TERM
                                                                                     COMPENSATION
                                                                                        AWARDS
                                                              ANNUAL COMPENSATION   ---------------
                                                                                      SECURITIES
                                                             ---------------------    UNDERLYING        ALL OTHER
                NAME AND PRINCIPAL POSITION                    SALARY      BONUS      OPTIONS (#)     COMPENSATION
- -----------------------------------------------------------  ----------  ---------  ---------------  ---------------
<S>                                                          <C>         <C>        <C>              <C>
Douglass B. Given, M.D., Ph.D.  ...........................  $  185,000  $  46,250        95,000        $   1,065(1)
 President and Chief Executive Officer
Doros Platika, M.D.(2) ....................................     135,000     35,700        40,000(3)        --
 Executive Vice President, Research and
 Development
H. Ralph Snodgrass, Ph.D.  ................................     109,000     30,000        30,000(4)        --
 Vice President, Research and Chief Scientific
 Officer
Stephen J. Williams, Ph.D.  ...............................     135,000     --            17,500           --
 Vice President, Corporate Development
</TABLE>
    
 
- --------------
(1) Consists of premiums paid by the Company on a term life insurance policy for
    Dr. Given.
 
(2) Dr. Platika's employment with the Company terminated effective as of May 24,
    1996,  pursuant  to  a  Separation  Agreement  and  Release.  See   "Certain
    Transactions -- Transactions with Directors and Executive Officers."
 
(3)  Includes options exercisable for 7,500 shares of Common Stock, all of which
    vested on  September  14, 1995,  the  date of  grant.  As a  result  of  the
    termination  of  Dr. Platika's  employment by  the Company,  options granted
    during fiscal 1995 that  were vested as of  May 24, 1996 remain  exercisable
    until  August 24,  1996, and  all other  options granted  during fiscal 1995
    terminated effective May 24, 1996 in  accordance with the terms of the  1992
    Stock  Option Plan. See "Certain Transactions -- Transactions with Directors
    and Executive Officers."
 
(4) Includes options exercisable for 12,500 shares of Common Stock, all of which
    vest upon the earliest of the achievement of performance milestones relating
    to the  leptin receptor  program  or the  BFU-e  growth factor  program,  or
    September 14, 2002.
 
COMPENSATION COMMITTEE INTERLOCKS AND INSIDER PARTICIPATION
 
    The Board of Directors did not have a Compensation Committee in fiscal 1995.
All  deliberations with regard to executive  compensation were by the full Board
of Directors. Dr. Cooper,  the former President and  Chief Executive Officer  of
the  Company,  participated  as a  director  in these  deliberations.  Dr. Given
participated as  a director  in  deliberations and  voting  with regard  to  the
compensation  of  Drs.  Platika,  Snodgrass  and  Williams,  but  abstained from
deliberations and voting with regard to his own compensation.
 
                                       43
<PAGE>
STOCK PLANS
 
1992 STOCK OPTION PLAN
 
    The 1992  Stock  Option  Plan was  adopted  and  approved by  the  Board  of
Directors  in December 1992 and  by the stockholders of  the Company in February
1993. The plan was amended with the  approval of the Board of Directors and  the
stockholders  in September 1995 to increase the number of shares of Common Stock
available for  grant.  A total  of  500,000 shares  of  Common Stock  have  been
reserved  for issuance under the  1992 Stock Option Plan,  as amended. As of May
31, 1996, options  to purchase 6,675  shares of Common  Stock granted under  the
1992 Stock Option Plan had been exercised, options to purchase 376,000 shares of
Common  Stock were outstanding and options  to purchase 117,325 shares of Common
Stock remained available  for grant.  The outstanding  options were  held by  38
individuals  and were exercisable at a  weighted average exercise price of $4.70
per share. Outstanding options  to purchase an aggregate  of 32,500 shares  were
held  by employees who  are not officers  or directors of  the Company. The 1992
Stock Option Plan will terminate in 2002, unless sooner terminated by the  Board
of Directors.
 
    The  Board of  Directors currently administers  the 1992  Stock Option Plan.
Prior to  the  closing  of  the  Offering, the  Board  intends  to  designate  a
Compensation  Committee and delegate to it  the administration of the 1992 Stock
Option Plan. The Compensation Committee will  be constituted to comply with  the
rules  governing a plan intended  to qualify as a  discretionary plan under Rule
16b-3 of the Securities Exchange Act of 1934. Awards under the 1992 Stock Option
Plan may consist of (i)  options to purchase Common  Stock that are designed  to
qualify, under Section 422 of the Internal Revenue Code of 1986, as amended (the
"Code"),  as  "incentive  stock  options" ("Incentive  Stock  Options")  or (ii)
options to purchase Common Stock that are  not described in Sections 422 or  423
of  the  Code ("Non-Qualified  Stock Options"  and, collectively  with Incentive
Stock Options, "Options").
 
    The Board of Directors  has discretion to grant  Incentive Stock Options  to
employees and officers (including officers who are directors) of the Company and
Non-Qualified  Stock Options to employees,  officers (including officers who are
directors), directors, independent contractors  and consultants of the  Company.
The  Board may set the terms of  such grants, subject to applicable restrictions
in the 1992 Stock Option Plan. Incentive Stock Option grants are subject to  the
following  limitations: (i) the  term of any  Incentive Stock Option  may not be
longer than ten  years, provided  that the term  of any  Incentive Stock  Option
granted  to an individual possessing more than  10% of the combined voting power
of the Company  or an affiliate  (a "10% Holder")  may not be  longer than  five
years;  (ii) the aggregate fair market  value of all shares underlying Incentive
Stock Options granted  to an  individual that  first become  exercisable in  any
calendar year may not exceed $100,000; and (iii) the exercise price of Incentive
Stock  Options may  not be  less than  the fair  market value  of the underlying
shares on the  grant date,  provided that the  exercise price  of any  Incentive
Stock  Option granted  to a 10%  Holder may  not be less  than 110%  of the fair
market value  of  the underlying  shares  on the  grant  date. With  respect  to
Non-Qualified Stock Options, the Board has discretion to grant such Options with
an exercise price below the fair market value of the Common Stock. As of May 31,
1996, no such below-market grants had been made.
 
    During an optionee's lifetime, an Option is exercisable only by the optionee
and  no Option may be transferred by the optionee other than by will or the laws
of descent and distribution. An optionee whose relationship with the Company  or
any related corporation ceases for any reason (other than termination because of
death  or total  disability) may exercise,  in the  three-month period following
such cessation (unless such Options terminate or expire sooner by their  terms),
or such longer period as determined by the Board, that portion of the optionee's
Options  that is  exercisable at the  time of  such cessation. In  the event the
optionee dies or becomes totally disabled, the Options vested as of the date  of
death or total disability may be exercised prior to the earlier of such Option's
specified  expiration date or one year from  the date of the optionee's death or
disability.
 
   
    Unexercised Options granted under the 1992 Stock Option Plan terminate  upon
the occurrence of certain events, including a dissolution, liquidation or merger
or  consolidation  of the  Company in  which  the Company  is not  the surviving
corporation.   All   outstanding   Options    vest   and   become    immediately
    
 
                                       44
<PAGE>
   
exercisable  prior  to the  effective time  of any  such event.  In a  merger or
consolidation in which the Company is the surviving corporation, Options will be
deemed to apply to the numbers of  shares to which the holders thereof prior  to
such  merger would be entitled. The converted  Options would continue to vest in
accordance with the vesting schedule set by the Board for such Options.
    
 
    The Board of  Directors may  amend the 1992  Stock Option  Plan, insofar  as
permitted  by  law, with  respect to  any  shares of  Common Stock  reserved for
issuance but not yet subject to Options. Shares subject to Options granted under
the 1992 Stock Option Plan that have  lapsed or terminated may again be  subject
to  Options granted under the 1992 Stock Option Plan. Furthermore, the Board may
offer to exchange new Options for  existing Options, with the shares subject  to
the existing Options being again available for grant under the 1992 Stock Option
Plan.
 
1996 STOCK INCENTIVE PLAN
 
   
    The  1996 Stock Incentive Plan (the "1996 Plan") was adopted and approved by
the Board of Directors  in May 1996  and will be presented  for approval by  the
stockholders  of the Company  prior to the  closing of the  Offering. A total of
775,000 shares of Common  Stock have been reserved  for issuance under the  1996
Plan.  As  of May  31, 1996,  no options  issued  under the  1996 Plan  had been
exercised, options to purchase 275,000  shares of Common Stock were  outstanding
and  options to purchase  500,000 shares of Common  Stock remained available for
grant. Outstanding  options  under  the  1996 Plan  were  held  by  three  Named
Executive Officers and were exercisable at an exercise price of $9.00 per share.
No  options  were held  by  persons who  are not  officers  or directors  of the
Company. The 1996 plan will terminate  in May 2006, unless sooner terminated  by
the Board of Directors.
    
 
   
    Upon  the adoption and approval of the  1996 Plan by the stockholders of the
Company, the Board of Directors will delegate administration of the 1996 Plan to
the Compensation Committee  (the "Committee").  Awards under the  1996 Plan  may
consist  of (i) Incentive Stock Options, (ii) Non-Qualified Stock Options, (iii)
the sale  or bonus  grant  of restricted  shares  of Common  Stock  ("Restricted
Stock"),  (iv) the grant of stock  appreciation rights ("SARs"), either alone or
together with Options, (v) the grant  of dividend equivalent rights measured  by
dividends  paid with respect to the Common Stock ("DERs"), and (vi) the grant of
any of the  abovementioned options, rights  or shares based  upon attainment  of
certain performance criteria ("Performance Shares").
    
 
   
    The Committee will have discretion to grant Options, Restricted Stock, SARs,
DERs  and Performance Shares to employees,  officers (including officers who are
directors of the Company),  directors and consultants  of the Company,  provided
that  only employees  and officers  of the  Company may  receive Incentive Stock
Options. The Committee may set the  terms of such grants, subject to  applicable
restrictions  in the 1996  Plan. Incentive Stock  Option and Non-Qualified Stock
Option grants are subject to the same  limitations under the 1996 Plan as  those
discussed  above for the  1992 Stock Option Plan.  With respect to Non-Qualified
Stock Options, the Committee will have discretion to grant such Options with  an
exercise  price below the fair  market value of the Common  Stock. As of May 31,
1996, no such below-market grants had been made.
    
 
   
    Upon certain  changes in  control of  the Company  (as defined  in the  1996
Plan),  or  upon  the  merger  or  consolidation,  reverse  merger, dissolution,
liquidation or sale of all  or substantially all of  the assets of the  Company,
all  outstanding Options,  SARs, Restricted  Stock, DERs  and Performance Shares
will become fully  vested, nonforfeitable  and exercisable,  and any  Restricted
Stock  will be released from all restrictions on transfer and all repurchase and
forfeiture restrictions. Each Option,  SAR or DER  shall remain exercisable  for
the  remaining term of the  Option, SAR or DER, except  that each Option, SAR or
DER shall  terminate as  of the  effective date  of a  merger or  consolidation,
reverse  merger, dissolution, liquidation or sale of all or substantially all of
the assets of the Company.
    
 
   
    The Board  of  Directors  may  amend  the  1996  Plan,  and  any  agreements
evidencing awards granted thereunder, at any time and for any reason, subject to
certain  restrictions  on  the  ability to  adversely  affect  awards previously
granted thereunder and to any legal requirement to obtain stockholder approval.
    
 
                                       45
<PAGE>
EMPLOYMENT AGREEMENT
 
    On January  3,  1993,  the  Company  entered  into  a  four-year  employment
agreement  with Dr.  Given. The  agreement provides  for an  initial annual base
salary of $175,000, reviewable  annually by the Board  of Directors, and  annual
bonuses based on the achievement of performance milestones as mutually agreed by
the Board of Directors and Dr. Given. Under the agreement, Dr. Given was granted
the  right  to  purchase  3%  of  the shares  of  Common  Stock  of  the Company
outstanding as of the  date of the  agreement, or 82,907  shares, at a  purchase
price  of $.02 per share. Such stock is  subject to a repurchase option in favor
of the Company, exercisable upon termination  of Dr. Given's employment for  any
reason,  that expires equally with respect to  one-fourth of such shares on each
anniversary date of the agreement beginning on the first anniversary date.
 
   
    Under the agreement, Dr. Given received the right to a $100,000 loan bearing
interest at 7% annually for the purchase of a home in Ohio. Upon the granting of
the loan, the Company waived the charging  of interest on the loan, and  certain
other  provisions of the agreement  relating to the loan,  and received from Dr.
Given an interest-free promissory note in the amount of $100,796 secured by  the
property purchased. The note requires Dr. Given to repay at least $60,796 of the
loan on or before April 1, 1997. Of this portion, $20,000 was forgiven effective
in  fiscal 1996 at the  approval of the Board  of Directors, and $40,796 remains
payable. The balance of $40,000 is payable  on or before April 15, 1997 or  upon
the  termination  of Dr.  Given's employment  and is  subject to  forgiveness in
$10,000 increments  upon  the  achievement of  certain  performance  milestones,
including a successful initial public offering of the Company's Common Stock. As
of  March 31, 1996, the Company had  forgiven, effective in fiscal 1996, $10,000
of  the  loan  pursuant  to   this  provision.  See  "Certain  Transactions   --
Transactions with Directors and Executive Officers."
    
 
    The  agreement also  provides that,  during the  term of  the agreement and,
unless Dr.  Given  terminates  his  employment  for  cause  as  defined  in  the
agreement,  for  a  period  of  two  years  after  termination  of  Dr.  Given's
employment, he will not compete with the Company, directly or indirectly. In the
event the Board of Directors terminates Dr. Given's employment without cause, as
defined in the agreement, he would be entitled to his base salary plus pro-rated
average bonuses,  subject  to reduction  for  compensation received  from  other
employment, for a period of six months from the date of termination.
 
                    STOCK OPTION GRANTS IN LAST FISCAL YEAR
 
    The  following  table contains  information  concerning the  grant  of stock
options to the Named Executive Officers  during the fiscal year ended  September
30, 1995.
 
   
<TABLE>
<CAPTION>
                                                                                                             POTENTIAL REALIZABLE
                                                                                                               VALUE AT ASSUMED
                                                  NUMBER OF      PERCENT OF                                 ANNUAL RATES OF STOCK
                                                 SECURITIES     TOTAL OPTIONS                               PRICE APPRECIATION FOR
                                                 UNDERLYING      GRANTED TO       EXERCISE                    OPTION TERM($)(3)
                                                   OPTIONS      EMPLOYEES IN        PRICE      EXPIRATION   ----------------------
                     NAME                        GRANTED(#)    FISCAL YEAR(1)   ($/SHARE)(2)      DATE          5%         10%
- ----------------------------------------------  -------------  ---------------  -------------  -----------  ----------  ----------
<S>                                             <C>            <C>              <C>            <C>          <C>         <C>
Douglass B. Given, M.D., Ph.D.................      50,000(4)        26.60%       $    6.00       9/14/05   $  188,668  $  478,123
                                                    45,000(5)        23.94             6.00       9/14/05      169,802     430,310
Doros Platika, M.D.(6)........................      32,500(5)        17.29             6.00       5/24/96           --          --
                                                     7,500(7)         4.00             6.00       8/24/96        2,121       4,242
 
H. Ralph Snodgrass, Ph.D......................      17,500(5)         9.31             6.00       9/14/05       66,034     167,343
                                                    12,500(8)         6.65             6.00       9/14/05       47,167     119,531
Stephen J. Williams, Ph.D.....................      17,500(5)         9.31             6.00       9/14/05       66,034     167,343
</TABLE>
    
 
- --------------
(1)  Based on  an aggregate  of 188,000 options  granted to  employees in fiscal
    1995.
 
(2) All options were granted at an exercise price equal to the fair market value
    of the Common  Stock on the  date of grant,  as determined by  the Board  of
    Directors.
 
                                       46
<PAGE>
(3)  The potential realizable  value is based on  the term of  the option at its
    time of grant  (ten years, except  for options granted  to Dr. Platika  (see
    footnotes (6) and (7)). It is calculated by assuming that the stock price on
    the  date  of grant  appreciates at  the  indicated annual  rate, compounded
    annually for the entire term of the option, and that the option is exercised
    and sold on the  last day of  its term for the  appreciated stock price.  No
    gain  to the optionee is possible unless  the stock price increases over the
    option term, which will benefit all stockholders.
 
(4) Consists of options that vest  equally over three years on each  anniversary
    of the date of grant, September 14, 1995.
 
   
(5)  Consists of options that were under the terms of the original grant to vest
    on the earlier of September 14, 2002 or a prior change in the control of the
    Company. On May 13, 1996, the Company's Board of Directors amended the terms
    of options to acquire an aggregate of 80,000 shares that had been granted to
    Drs. Given, Snodgrass  and Williams  so that  they vest  equally over  three
    years  on each  anniversary of  the date of  grant, September  14, 1995. See
    "Certain  Transactions  --   Transactions  with   Directors  and   Executive
    Officers."
    
 
   
(6) Dr. Platika's employment with the Company terminated effective as of May 24,
    1996, pursuant to a Separation Agreement and Release. Of the options granted
    during  fiscal 1995,  those vested  as of  May 24,  1996, remain exercisable
    until August 24,  1996, and  all other  options granted  during fiscal  1995
    terminated  effective May 24, 1996 in accordance  with the terms of the 1992
    Stock Option Plan. See "Certain Transactions -- Transactions with  Directors
    and Executive Officers."
    
 
(7)  Consists of options that vested immediately on the date of grant, September
    14, 1995.
 
(8) Consists  of options  that vest  upon  the earliest  of the  achievement  of
    performance  milestones relating to the leptin receptor program or the BFU-e
    growth factor program, or September 14, 2002.
 
                         FISCAL YEAR-END OPTION VALUES
 
    For each  of  the  Named  Executive  Officers,  the  following  table  shows
information  about the value of unexercised options as of September 30, 1995. No
options were exercised by the Named Executive Officers during fiscal 1995.
 
<TABLE>
<CAPTION>
                                                              NUMBER OF SECURITIES
                                                             UNDERLYING UNEXERCISED       VALUE OF UNEXERCISED
                                                               OPTIONS AT FISCAL        IN-THE-MONEY OPTIONS AT
                                                                  YEAR-END(#)            FISCAL YEAR-END($)(1)
                                                           --------------------------  --------------------------
                          NAME                             EXERCISABLE  UNEXERCISABLE  EXERCISABLE  UNEXERCISABLE
- ---------------------------------------------------------  -----------  -------------  -----------  -------------
<S>                                                        <C>          <C>            <C>          <C>
Douglass B. Given, M.D., Ph.D............................       4,125       107,375     $   8,250     $  24,750
Doros Platika, M.D.(2)...................................      23,750        53,750        84,750        94,750
H. Ralph Snodgrass, Ph.D.................................       6,250        38,750        20,000        20,000
Stephen J. Williams, Ph.D................................       5,000        32,500        10,000        30,000
</TABLE>
 
- --------------
(1) Based on the fair market value of the Common Stock as of September 30,  1995
    ($6.00  per share),  minus the exercise  price, multiplied by  the number of
    shares underlying the option.
 
   
(2) Dr. Platika's employment with the Company terminated effective as of May 24,
    1996,  pursuant  to  a  Separation  Agreement  and  Release.  See   "Certain
    Transactions -- Transactions with Directors and Executive Officers."
    
 
                                       47
<PAGE>
                              CERTAIN TRANSACTIONS
 
RELATIONSHIP WITH INTERNEURON
 
    Progenitor  was incorporated in February 1992 as a majority-owned subsidiary
of Interneuron and assumed all rights and obligations of Scimark Corp. under the
January  1992  research  and  licensing  agreement  with  Ohio  University.  See
"Business   --  License  Agreements  --   Ohio  University."  Upon  Progenitor's
organization, Interneuron purchased 2,081,250 shares  of Common Stock for  $.002
per  share. Progenitor  also issued 112,500  and 56,250 shares  of Common Stock,
respectively, to Morris  Laster, M.D.,  a director  of the  Company, and  Steven
Kanzer,  then Assistant Secretary of the Company,  for a purchase price of $.002
per share. Lindsay Rosenwald,  M.D., the Chairman of  the Board and a  principal
stockholder  of Interneuron, was  the Company's President  until September 1992,
and was a director of  the Company until May 1996.  Dr. Rosenwald also owns  the
Castle  Group  Ltd.  ("Castle"), a  venture  capital  firm. Dr.  Laster  was the
Company's Chief Executive Officer until September  1992, and Dr. Laster and  Mr.
Kanzer were and continue to be employees of Castle.
 
    From  Progenitor's  inception  through  December  1994,  Interneuron  funded
Progenitor's operations through advances  evidenced by promissory notes  payable
on demand and bearing interest at 1% over the prime rate. In December 1994, upon
the  initial closing of  the private placement referred  to below, the aggregate
amount of such advances of approximately $11.5 million, plus accrued interest of
approximately $1.1 million, was  converted by Interneuron  into an aggregate  of
2,020,496  shares of  Series A  Preferred Stock of  the Company  at a conversion
price of $6.25  per share. These  shares will convert  into 1,512,741 shares  of
Common Stock upon the closing of the Offering. See "Description of Capital Stock
- -- Preferred Stock."
 
   
    Between December 1994 and July 1995, Progenitor issued and sold an aggregate
of  349,000 shares  of Series  B Preferred Stock  in a  private placement. These
shares will convert into 261,273 shares of Common Stock upon the closing of  the
Offering.  See "Description  of Capital Stock  -- Preferred  Stock." The private
placement was  a sale  of units,  each unit  consisting of  Series B  shares  of
Preferred  Stock  of the  Company,  shares of  preferred  stock of  Transcell, a
subsidiary of Interneuron, a put protection right from Interneuron and  warrants
to  purchase Interneuron's common stock. The  put protection right provides that
on the third  anniversary of the  final closing date  of the private  placement,
holders  of such Series B Preferred Stock  have the right to sell to Interneuron
their Series B Preferred Stock  of Progenitor at a  purchase price equal to  the
purchase price of such shares in the private placement. The put protection right
will  expire upon the closing of the Offering. Of the approximately $4.4 million
gross proceeds of the private placement, Progenitor received approximately  $1.6
million,  net  of placement  agent fees  and Interneuron  received approximately
$833,000 from the proceeds of the private placement as its consideration for the
issuance of warrants for its common stock and the put protection right. Of  this
amount,  Interneuron loaned approximately $417,000 to Progenitor in exchange for
a convertible debenture dated  March 31, 1995, bearing  interest at 1% over  the
prime  rate. The principal amount of this debenture and accrued interest thereon
(approximately $463,000 as of May 31, 1996), will automatically be converted  at
the  closing of the Offering  into shares of Common  Stock at a conversion price
equal to the initial public offering price. See "Description of Capital Stock --
Interneuron Convertible Debenture and Promissory Note."
    
 
    Paramount Capital, Inc. ("Paramount") acted  as the placement agent for  the
private  placement and D.H. Blair  & Co., Inc. ("Blair")  was a selected dealer.
Paramount is owned  by Dr.  Rosenwald. Progenitor  paid Paramount  approximately
$129,000  as its share  of placement agent fees.  Pursuant to Paramount's rights
under its  placement agent  agreement, designees  of Paramount  received in  the
private placement warrants to purchase an aggregate of 22,201 shares of Series B
Preferred  Stock (representing  the right  to purchase  16,619 shares  of Common
Stock following the closing of the Offering). Dr. Rosenwald received warrants to
purchase 12,274 of these  shares of Series B  Preferred Stock (representing  the
right  to purchase  9,189 shares  of Common Stock  following the  closing of the
Offering). Blair is  substantially owned by  family members of  J. Morton  Davis
(including members of Dr. Rosenwald's family), a principal
 
                                       48
<PAGE>
stockholder  of Interneuron. Blair received fees  for acting as selected dealer,
aggregating $45,094. Designees of Blair  also received in the private  placement
warrants  to purchase an aggregate of 12,700  shares of Series B Preferred Stock
(representing the right to purchase 9,507  shares of Common Stock following  the
closing of the Offering). All of these warrants are exercisable until five years
after  the closing of  the Offering at an  exercise price of  $9.18 per share of
Common Stock, and  pursuant to a  cashless exercise provision  may be  exercised
without  the need to  pay any cash.  See "Description of  Capital Stock -- Stock
Purchase Right and Warrants." The Company also agreed to indemnify Paramount and
Blair against certain  liabilities, including liabilities  under the  Securities
Act  in connection with the private placement. See "Description of Capital Stock
- -- Stock Purchase Right and Warrants."
 
    Since  March  1996,  Interneuron  has  continued  to  provide  advances   to
Progenitor.  These advances are  evidenced by a promissory  note dated March 31,
1996, in the principal amount of approximately $523,000, as updated from time to
time, payable on  the earlier of  five years from  the date of  the note or  the
closing  of the Offering.  Interneuron has agreed  to convert at  the closing of
this Offering  the entire  indebtedness  evidenced by  the note,  including  the
original  principal balance, additional advances from  April 1, 1996 through the
closing of the Offering, and all accrued interest (an aggregate of $1.2  million
of  principal and accrued interest as of May 31, 1996) into shares of Progenitor
Common Stock at a conversion price  equal to the initial public offering  price.
See  "Description  of Capital  Stock  -- Interneuron  Convertible  Debenture and
Promissory Note."
 
    Based on the amount owed by  Progenitor to Interneuron under the  promissory
note  as of May 31, 1996, and as a  result of the conversion upon the closing of
the Offering  of  the  Series  A  Preferred  Stock,  convertible  debenture  and
promissory  note held by Interneuron, Interneuron  will own 3,736,017 shares, or
51.2% of Progenitor's outstanding Common Stock after closing of the Offering.
 
   
    During fiscal 1995, Interneuron paid  for certain Progenitor expenses  which
were  reimbursed  by Progenitor  at  cost. In  addition,  Interneuron guaranteed
Progenitor's office lease (which guarantee will be released upon the closing  of
the  Offering as to obligations  arising after the closing  of the Offering) and
its equipment leases.  Prior to  the closing of  the Offering,  the Company  and
Interneuron  expect to enter  into a tax allocation  agreement to provide, among
other things,  for  the payment  of  tax  liabilities, the  entitlement  to  tax
refunds,  and the allocation of responsibility  and cooperation in the filing of
tax returns. In addition,  the Company and Interneuron  intend to enter into  an
intercompany  services agreement which may provide, among other things, for: the
participation of the Company and its employees in certain programs  administered
by Interneuron, at cost, such as certain insurance; and the provision of certain
services  by Interneuron at Progenitor's request  at agreed upon prices in areas
such  as   clinical   and   regulatory  affairs,   quality   control,   finance,
administration,   human  resources  and   management  information  systems.  The
intercompany services agreement is also expected to provide that in the event of
any future equity offering  by the Company, Interneuron  will have the right  to
purchase  (at the same  price and on the  same terms as  such equity offering) a
portion of the shares being offered so as to maintain its fully-diluted interest
in Progenitor  immediately prior  to such  equity offering,  subject to  certain
limitations.  The Company also expects  that the intercompany services agreement
will provide that all  future transactions between  the Company and  Interneuron
must  be on terms no  less favorable to the Company  than could be obtained from
unaffiliated third parties and must be approved or ratified by a majority of the
independent members  of the  Company's Board  of Directors.  As expected  to  be
defined  in the intercompany services agreement, independent directors are those
who are not  employees, officers, directors  or affiliates of,  or persons  with
other  material  financial  interests  involving, Interneuron  or  any  of their
respective affiliates.
    
 
    After the Offering,  Interneuron will  continue to control  the election  of
directors  of  the  Company and  voting  with  respect to  matters  submitted to
stockholders, including extraordinary corporate transactions such as a merger or
sale of substantially all of the Company's assets. Interneuron's ownership of  a
substantial  block  of  the Company's  voting  stock  could have  the  effect of
delaying or preventing sales of additional  securities of the Company or a  sale
of the Company or other change of control supported by the other stockholders of
the  Company. In addition, the  Company may be subject  to various risks arising
from Interneuron's influence over the  Company, including conflicts of  interest
relating to new business
 
                                       49
<PAGE>
opportunities  that could be  pursued by the  Company or by  Interneuron and its
other affiliates, and significant  corporate transactions for which  stockholder
approval  is required. See "Risk Factors -- Control of Company By, and Potential
Conflicts of Interest With, Interneuron."
 
    Interneuron has no obligation to invest any further funds in the Company  or
otherwise  provide funding  to the Company  after the Offering,  and the Company
does not expect  Interneuron to do  so. The Company  intends to seek  additional
funding  through public  or private equity  or debt  financing and collaborative
arrangements. There  can  be no  assurance  that additional  financing  will  be
available  when needed, or that, if  available, such financing will be available
on terms acceptable  to the Company.  See "Risk Factors  -- Need for  Additional
Capital; Uncertainty of Additional Funding."
 
    Interneuron has entered into a lock-up agreement which limits its ability to
sell  shares of the  Company's Common Stock during  the 365-day period following
the date  of  this  Prospectus.  See  "Shares  Eligible  for  Future  Sale"  and
"Underwriting."
 
THE OHIO UNIVERSITY FOUNDATION
 
    Upon   the  Company's  formation  in  February  1992,  The  Ohio  University
Foundation purchased 125,000 shares of Common Stock at a purchase price of $.002
per share,  and  Dr.  Thomas Wagner,  an  employee  of Ohio  University  and  an
affiliate  of The Ohio University Foundation, purchased 125,000 shares of Common
Stock at $.002  per share.  Pursuant to  certain antidilution  rights, The  Ohio
University  Foundation was  issued an additional  53,750 shares  of Common Stock
from fiscal  1992  through fiscal  1994.  Also,  in December  1994,  Dr.  Wagner
received  an  additional  53,750  shares of  Common  Stock  pursuant  to similar
antidilution provisions  contained in  a related  stock purchase  agreement.  In
February  1996, The  Ohio University  Foundation purchased  an additional 58,333
shares of Common Stock  for a purchase  price of $6.00 per  share pursuant to  a
stock purchase agreement. In the event the initial public offering price is less
than  $12.00  per share,  pursuant to  such stock  purchase agreement,  The Ohio
University Foundation will be  entitled to receive  additional shares of  Common
Stock such that the price per share paid by The Ohio University Foundation under
the  agreement  is  equal  to  50% of  the  initial  public  offering  price. In
connection with such purchase,  the Company and  The Ohio University  Foundation
amended  certain provisions of the 1992 stock purchase agreement in exchange for
which Progenitor granted The  Ohio University Foundation  the right to  purchase
25,000  shares of Progenitor Common Stock at a price equal to 50% of the initial
public offering price.  The Ohio  University Foundation has  agreed to  exercise
such  right to  purchase 25,000  shares immediately prior  to the  Offering at a
price of $6.00 per share.
 
   
    Ohio University entered into license and sponsored research agreements  with
the Company (or its predecessor) in January 1992 and April 1993. Pursuant to the
initial  license  agreement, The  Ohio University  Foundation  has the  right to
designate two members of Progenitor's Board of Directors until the completion of
Progenitor's initial public offering. Messrs. Axline and Peppers are Trustees of
The Ohio University  Foundation and  serve as The  Ohio University  Foundation's
designees  to Progenitor's Board of Directors. Under the Ohio University license
and sponsored research agreements, Progenitor paid Ohio University an  aggregate
of  approximately $570,000, $246,000, $397,000 and $66,000 in fiscal 1993, 1994,
1995, and for the six months ended March 31, 1996, respectively. Ohio University
also is entitled to  receive royalties based on  any sales of licensed  products
resulting  from such arrangements. Under a  consulting agreement with Dr. Wagner
entered into in  February 1992, Progenitor  paid Dr. Wagner  consulting fees  of
approximately  $93,000, $93,000, $113,000 and  $30,000 during fiscal 1993, 1994,
1995, and for the six months  ended March 31, 1996, respectively. See  "Business
- -- License Agreements."
    
 
TRANSACTIONS WITH DIRECTORS AND EXECUTIVE OFFICERS
 
    Dr.  Cooper served as the Company's President from September 1992 until June
1994. In September 1992, the Company loaned Dr. Cooper $150,000 to assist him in
purchasing a new home in the state of
 
                                       50
<PAGE>
Ohio. In October  1993, Dr.  Cooper repaid  the loan  in full.  Pursuant to  Dr.
Cooper's  employment agreement,  Dr. Cooper  purchased 133,681  shares of Common
Stock at  $.02 per  share, subject  to the  Company's right  to repurchase  such
shares  over a three-year period. In May  1993, upon Dr. Cooper's appointment as
president of Interneuron, the repurchase option was modified at the approval  of
the  Board  of Directors  and  the Company  repurchased  74,267 of  Dr. Cooper's
shares.
 
   
    On January 3, 1993,  the Company entered into  an employment agreement  with
Dr.  Given. Under the agreement, Dr. Given received the right to a $100,000 loan
bearing interest at 7%  annually for the  purchase of a home  in Ohio. Upon  the
granting  of the loan, the Company waived  the charging of interest on the loan,
and certain other provisions of the agreement relating to the loan, and received
from Dr.  Given an  interest-free  promissory note  in  the amount  of  $100,796
secured by the property purchased. The note requires Dr. Given to repay at least
$60,796  of the loan  on or before April  1, 1997. Of  this portion, $20,000 was
forgiven effective in fiscal 1996 at the approval of the Board of Directors, and
$40,796 remains payable. The  balance of $40,000 is  payable on or before  April
15,  1997 or upon  the termination of  Dr. Given's employment  and is subject to
forgiveness in $10,000  increments upon the  achievement of certain  performance
milestones,  including  a successful  initial public  offering of  the Company's
Common Stock.  As of  March 31,  1996, the  Company had  forgiven, effective  in
fiscal  1996, $10,000 of the loan pursuant to this provision. Upon completion of
the Offering, an  additional $10,000 of  the loan will  be forgiven pursuant  to
this provision. See "Management -- Employment Agreement."
    
 
   
    The  Company provided Dr. Williams with a  $55,000 down payment loan for the
purchase of a home in Ohio upon the commencement of his employment in June 1994.
This loan  is evidenced  by a  promissory  note executed  in fiscal  1995  which
accrues  interest at 9% annually and is secured by Dr. Williams' home. Under the
terms of the promissory  note, $40,000 of this  loan, plus accrued interest,  is
subject to forgiveness by the Board of Directors upon the achievement of certain
performance  milestones. Pursuant  to this  arrangement, the  Board of Directors
approved forgiveness  effective in  fiscal 1996  of $20,000  of the  loan,  plus
associated  accrued interest. The  Board of Directors  also approved forgiveness
effective in fiscal 1996  of an additional $8,000  of the loan, plus  associated
accrued  interest,  in  lieu  of  a salary  increase.  The  balance  of $30,119,
including accrued  interest as  of  March 31,  1996, remains  outstanding.  Upon
completion  of the Offering, an additional  $10,000 of the loan, plus associated
accrued interest, will be forgiven. In addition, the Company loaned Dr. Williams
$21,448 in fiscal 1995. This amount was repaid in May 1996.
    
 
   
    Effective as  of May  24, 1996,  Dr. Doros  Platika's employment  terminated
pursuant  to  a  Separation  Agreement and  Release  (the  "Release")  among the
Company, Dr.  Platika and  Interneuron.  The Release  obligates Dr.  Platika  to
provide services to the Company in a consulting capacity for a minimum of twenty
hours  per month for  the six-month period  following May 24,  1996. Dr. Platika
also agreed not to compete with the Company for a period of two years after  his
termination.  The Release also contains arrangements  with respect to loans made
by the Company to Dr. Platika and certain stock options to acquire securities of
the Company and Interneuron. Prior to termination, the Company had made loans to
Dr. Platika that had a balance of $207,378, including accrued interest as of May
24, 1996, which  amount reflects  the forgiveness  effective in  fiscal 1996  of
$26,652 of such loans previously approved by the Board of Directors. Pursuant to
the  Release, an additional $120,000 of this balance was forgiven subject to Dr.
Platika's payment to the Company  of withholding payments required with  respect
thereto  and with respect to the loans to Dr. Platika previously forgiven by the
Company effective in fiscal 1996. The remaining balance of Dr. Platika's loan is
payable on or prior to July 23, 1996 in cash, or to the extent not paid in cash,
then by means of  surrendering to the  Company shares of  Common Stock or  stock
options with value equivalent to the loan balance (valuing the options on a "net
exercise basis") based upon a $9.00 price per share of Common Stock. The Company
will  incur a charge  to operations equal  to the amount  of loan forgiveness in
connection with the  Release, and  equal to  the amount  of any  portion of  the
remaining  loan balance  that is  not repaid in  cash, but  is instead satisfied
through the surrender  of Common  Stock or options.  Prior to  the Release,  the
Company  had granted Dr. Platika options to purchase a total of 77,500 shares of
Common Stock,  at exercise  prices ranging  from $0.20  to $6.00  per share.  Of
these,  options  to  purchase a  total  of  23,750 shares  of  Common  Stock had
previously vested. The
    
 
                                       51
<PAGE>
   
Release provides for the vesting as of June 1, 1996 of options to purchase 6,875
shares of Common Stock at $0.20 per share and the vesting as of June 15, 1996 of
options to acquire 2,500 shares of Common  Stock at $4.00 per share. All of  Dr.
Platika's  other unvested options were canceled pursuant to the Release. On June
15, 1996, Dr. Platika will hold options exercisable for 33,125 shares of  Common
Stock, which options will expire on August 24, 1996 in accordance with the terms
of  the  1992 Stock  Option Plan.  In connection  with the  Release, Interneuron
agreed to  accelerate vesting  of  stock options  to  purchase 2,500  shares  of
Interneuron  Common Stock at a  price per share of  $8.75, which options will be
exercisable by Dr. Platika on or prior to August 24, 1996.
    
 
    The Company  has  granted  stock  options to  its  directors  and  executive
officers  on several occasions since the beginning  of fiscal 1993, all of which
vest over a four-year period from the date of grant, except as indicated  below.
In  fiscal  1993, Dr.  Snodgrass received  options to  purchase 5,000  shares of
Common Stock at an exercise  price of $0.20 per  share, and options to  purchase
5,000  shares of Common  Stock at an exercise  price of $2.00  per share and Dr.
Platika received options to purchase 7,500 shares of Common Stock at an exercise
price of $6.00  per share,  all of  which vested  immediately upon  the date  of
grant.
 
    During  fiscal 1994, Mr. Sharrock received  options to purchase 2,500 shares
of Common Stock at an exercise price  of $4.00 per share, which vest over  three
years.  Also in fiscal  1994, the Company granted  Drs. Cooper, Given, Snodgrass
and Williams options  to purchase  8,500, 16,500,  10,000 and  20,000 shares  of
Common Stock, respectively, at an exercise price of $4.00 per share.
 
    In  September 1995, the Company granted options to Drs. Given, Snodgrass and
Williams to  purchase 45,000,  17,500  and 17,500  shares, respectively,  at  an
exercise  price of $6.00  per share, which  originally were intended  to vest on
September 14, 2002. These options were amended by the Board of Directors on  May
13, 1996, so that one-third of such options vest on each anniversary date of the
date  of grant. In September  1995, the Company granted  to Dr. Given options to
purchase an additional 50,000  shares at an exercise  price of $6.00 per  share,
which  also vest over three years from the  date of grant. In September 1995 the
Company also  granted to  Dr. Snodgrass  options to  purchase 12,500  shares  of
Common  Stock,  all  of which  vest  upon  the earliest  of  the  achievement of
performance milestones  relating to  the leptin  receptor program  or the  BFU-e
growth factor program, or September 14, 2002.
 
    On  February 21,  1996, each of  Messrs. Axline, Haig,  Peppers and Sharrock
received options to purchase 7,500 shares  of Common Stock at an exercise  price
of $6.00 per share.
 
    All  of the  option grants  described above were  made pursuant  to the 1992
Stock Option Plan.
 
    On May 13, 1996, in connection with the Board of Directors' adoption of  the
Company's  1996 Stock  Incentive Plan, Drs.  Given, Snodgrass  and Williams were
granted options, which vest over three  years, to purchase 100,000, 100,000  and
75,000  shares of Common Stock, respectively, at  an exercise price of $9.00 per
share.
 
INSIDER TRANSACTIONS
 
   
    The Company has adopted  a policy that all  future transactions between  the
Company  and  its executive  officers, directors  and  other affiliates  must be
approved by a majority  of the disinterested members  of the Company's Board  of
Directors,  and must be on terms no less  favorable to the Company than could be
obtained from unaffiliated third parties. In addition, this policy requires that
any loans  by  the  Company  to  its  executive  officers,  directors  or  other
affiliates  be for  bona fide business  purposes only. A  determination of which
directors are disinterested with respect to a particular transaction will depend
upon the totality  of circumstances  including whether the  directors possess  a
direct  or indirect  material interest  in the  transaction or  in another party
involved in the transaction.
    
 
                                       52
<PAGE>
                             PRINCIPAL STOCKHOLDERS
 
    The following  table sets  forth  certain information  regarding  beneficial
ownership  of the Company's Common Stock as of  May 31, 1996, and as adjusted to
reflect the sale of the shares of Common Stock being offered hereby, by (i) each
stockholder who is known by the Company to own beneficially more than 5% of  the
Company's  outstanding  Common Stock,  (ii)  each director  and  Named Executive
Officer of the  Company and (iii)  all directors and  executive officers of  the
Company as a group.
 
<TABLE>
<CAPTION>
                                                                                     PERCENTAGE BENEFICIALLY
                                                                        NUMBER OF            OWNED(2)
                                                                         SHARES     --------------------------
                                                                       BENEFICIALLY   PRIOR TO       AFTER
BENEFICIAL OWNER                                                        OWNED(1)      OFFERING      OFFERING
- ---------------------------------------------------------------------  -----------  ------------  ------------
<S>                                                                    <C>          <C>           <C>
Glenn L. Cooper, M.D.(3) ............................................   3,741,767         78.0%         51.3%
 One Ledgemont Center
 99 Hayden Avenue
 Lexington, Massachusetts 02173
Interneuron Pharmaceuticals, Inc. ...................................   3,736,017         77.9          51.2
 One Ledgemont Center
 99 Hayden Avenue
 Lexington, Massachusetts 02173
The Ohio University Foundation (4) ..................................     262,083          5.5           3.6
 102 Research and Technology Center
 Athens, Ohio 45701
Morris Laster, M.D...................................................     112,500          2.3           1.5
Douglass B. Given, M.D., Ph.D. (5)...................................      91,157          1.9           1.2
H. Ralph Snodgrass, Ph.D. (6)........................................      12,500        *             *
Stephen J. Williams, Ph.D. (7).......................................      10,000        *             *
David B. Sharrock (8)................................................       1,666        *             *
Robert P. Axline.....................................................          --        *             *
Alexander M. Haig, Jr................................................          --        *             *
Jerry P. Peppers.....................................................          --        *             *
                                                                        3,969,590         82.8          54.1
All executive officers and directors as a group
 (9 persons) (9).....................................................
</TABLE>
 
- ------------------
*   Less than one percent.
 
(1)  To the Company's  knowledge, except as  indicated in the  footnotes to this
    table and subject to applicable community property laws, each of the persons
    named in this table has sole voting and investment power with respect to all
    shares of Common Stock indicated opposite such person's name.
 
(2) Percentage of beneficial  ownership is based on  4,793,819 shares of  Common
    Stock  outstanding as of May 31, 1996,  and 7,293,819 shares of Common Stock
    outstanding after completion of this Offering, reflecting the conversion  of
    the  convertible debenture and  promissory note held  by Interneuron and all
    outstanding shares of Preferred Stock into Common Stock and the purchase  by
    The  Ohio University Foundation of 25,000 shares of Common Stock pursuant to
    a stock purchase  right. See  "Capitalization" and  "Description of  Capital
    Stock."  Shares of Common Stock subject to options, warrants and convertible
    notes currently exercisable  or convertible, or  exercisable or  convertible
    within  60 days of  May 31, 1996,  are deemed outstanding  for computing the
    percentage of  the person  or entity  holding such  securities but  are  not
    deemed  outstanding  for computing  the percentage  of  any other  person or
    entity.
 
(3) Includes 3,736,017 shares held by Interneuron, options exercisable for 4,250
    shares of Common Stock held by Dr. Cooper and options exercisable for  1,500
    shares  of Common Stock held by Dr.  Cooper's wife. Dr. Cooper is President,
    Chief Executive Officer and a director of Interneuron. Dr. Cooper  disclaims
    beneficial ownership of the shares held by Interneuron.
 
(4) Includes a stock purchase right for 25,000 shares of Common Stock.
 
   
(5) Includes 82,907 shares held by a limited partnership of which Dr. Given is a
    general partner and options exercisable for 8,250 shares of Common Stock.
    
 
(6) Includes options exercisable for 12,500 shares of Common Stock.
 
(7) Includes options exercisable for 10,000 shares of Common Stock.
 
(8) Includes options exercisable for 1,666 shares of Common Stock.
 
(9)  Includes  options  exercisable  for  38,166  shares  of  Common  Stock. See
    footnotes 3, 5, 6, 7 and 8 above.
 
                                       53
<PAGE>
                          DESCRIPTION OF CAPITAL STOCK
 
   
    The  Company's Certificate of Incorporation, as amended (the "Certificate of
Incorporation")  currently  authorizes  42,000,000  shares  of  capital   stock,
consisting  of 39,000,000 shares of Common Stock,  Class A, $.001 par value, and
3,000,000 shares of  Preferred Stock,  $.01 par  value. In  connection with  the
Offering,  the  Company's  Certificate  of  Incorporation  will  be  amended and
restated (the "Restated Certificate of  Incorporation"). Upon completion of  the
Offering,  the Restated Certificate of Incorporation will authorize the issuance
of 44,000,000 shares of capital stock, consisting of 39,000,000 shares of Common
Stock, par value $.001 per share,  and 5,000,000 shares of Preferred Stock,  par
value  $.001 per share. Set forth below is a description of the capital stock of
the Company.
    
 
COMMON STOCK
 
    As of May  31, 1996, assuming  the conversion of  all outstanding shares  of
Preferred  Stock and the  convertible debenture and  promissory note into Common
Stock, and the exercise of the stock purchase right described below, there  were
4,793,819  shares of Common  Stock issued and  outstanding held of  record by 55
stockholders, 606,625  shares of  Common  Stock issuable  upon the  exercise  of
outstanding  stock options and  26,126 shares of Common  Stock issuable upon the
exercise of outstanding warrants.
 
    The holders  of Common  Stock are  entitled to  one vote  per share  on  all
matters  submitted to a vote of stockholders  and are not entitled to cumulative
voting rights with respect to the election of directors. Accordingly, holders of
a majority of the  shares of Common  Stock entitled to vote  in any election  of
directors  may  elect all  of the  directors standing  for election.  Holders of
Common Stock are entitled to receive ratably  such dividends, if any, as may  be
declared  by the  Board of  Directors out  of funds  legally available therefor,
subject to  preferences that  may  be applicable  to any  outstanding  Preferred
Stock.  In the event of  liquidation, dissolution or winding  up of the Company,
holders of  Common  Stock  are entitled  to  share  ratably in  all  net  assets
remaining  after payment  of liabilities and  the liquidation  preference of any
outstanding Preferred  Stock.  Holders  of  Common  Stock  have  no  preemptive,
subscription, redemption, conversion or other subscription rights, and there are
no  sinking  fund  provisions  applicable to  the  Common  Stock.  All currently
outstanding shares of  Common Stock are,  and the shares  of Common Stock  being
issued  and sold in the Offering will be, duly authorized, validly issued, fully
paid and nonassessable.
 
PREFERRED STOCK
 
    The Company currently has outstanding 2,020,496 shares of Series A Preferred
Stock and  349,000  shares  of  Series  B  Preferred  Stock.  Such  shares  will
automatically convert into Common Stock upon consummation of this Offering. Both
the  Series  A and  Series B  Preferred Stock  have antidilution  and conversion
adjustment provisions that  will increase or  decrease the number  of shares  of
Common  Stock outstanding as of May 31, 1996 above or below the number of shares
set forth herein  and will increase  or decrease  the number of  shares used  in
calculations  for purposes  of, among other  things, dilution  to new investors,
shares held by  certain principal stockholders,  shares subject to  registration
rights and shares eligible for future sale, in the event that the initial public
offering  price of the Common Stock offered hereby, is less than or greater than
$12.00 per share, as the case may be. See "Dilution," "Principal  Stockholders,"
"-- Registration Rights," and "Shares Eligible for Future Sale."
 
    The  actual number  of shares  of Common  Stock issuable  to each  holder of
Preferred Stock upon  conversion of the  Series A and  Series B Preferred  Stock
will  equal the product of  (a) the number of shares  of Preferred Stock held by
such holder multiplied  by (b) the  greater of (x)  one or (y)  a fraction,  the
numerator of which is $12.50 and the denominator of which is .6957 multiplied by
the  initial public offering  price of the  Common Stock offered  hereby. At the
assumed initial public offering price of  $12.00 per share, 1,774,014 shares  of
Common Stock will issue upon conversion of the Preferred Stock.
 
                                       54
<PAGE>
    Following  completion of the Offering and  the conversion of all outstanding
shares of Preferred  Stock, the Board  of Directors will  have the authority  to
issue from time to time up to 5,000,000 shares of Preferred Stock in one or more
series   and  to  fix  the   powers,  designations,  preferences  and  relative,
participating, optional  or other  rights  thereof, including  dividend  rights,
conversion  rights, voting rights, redemption terms, liquidation preferences and
the number of shares constituting each such series, without any further vote  or
action  by the  Company's stockholders.  The issuance  of Preferred  Stock could
adversely affect the rights of holders of Common Stock and could have the effect
of delaying, deferring  or preventing a  change in control  of the Company.  The
Company has no present plans to issue any shares of Preferred Stock.
 
STOCK PURCHASE RIGHT AND WARRANTS
 
    Pursuant  to a Stock Purchase  Agreement entered into on  March 27, 1992, as
amended on February 26, 1996, the Company granted The Ohio University Foundation
the right to purchase  up to 25,000 shares  of Common Stock in  the event of  an
initial public offering, merger or other similar corporate transaction involving
Progenitor, at a price equal to 50% of the assumed initial public offering price
per  share or other per share  consideration. The Ohio University Foundation has
agreed to exercise such right in full prior to the closing of the Offering.  See
"Certain Transactions -- The Ohio University Foundation."
 
   
    As  of  March  31, 1996,  there  were  warrants outstanding  to  purchase an
aggregate of 26,126 shares  of Common Stock  at an exercise  price of $9.18  per
share.  The  warrants also  contain a  cashless exercise  right that  allows the
holder to receive the number  of shares of Common  Stock subject to the  warrant
multiplied  by a fraction, the numerator of  which is the difference between the
then current  per share  market price  of the  Common Stock  and $9.18  and  the
denominator  of which is the  then current per share  market price of the Common
Stock. These warrants  were issued  in connection  with a  private placement  of
Preferred  Stock  for which  Paramount, an  affiliate  of Interneuron,  acted as
placement agent. See  "Certain Transactions --  Relationship with  Interneuron."
The  warrants expire five years  from the date of  this Offering. Upon automatic
conversion  of  the   outstanding  Preferred  Stock   in  connection  with   the
consummation of this Offering, all such warrants will be converted into warrants
to  purchase shares of  Common Stock. The  number of shares  of Common Stock for
which such warrants  are exercisable  is subject  to adjustment  if the  initial
public offering price of the Common Stock offered hereby is less than or greater
than  $12.00 per  share in  the same  manner and  according to  the same formula
described above  for  the  conversion of  the  Company's  currently  outstanding
Preferred  Stock. See "-- Preferred Stock." The  warrants do not confer upon the
holder thereof  any  voting or  preemptive  rights, or  any  other rights  as  a
stockholder  of Progenitor  prior to exercise.  Upon exercise  of such warrants,
holders of the  underlying shares of  Common Stock will  be entitled to  certain
registration rights with respect to such shares. See "-- Registration Rights."
    
 
REGISTRATION RIGHTS
 
   
    Pursuant  to Investors' Rights Agreements (the "Investors' Agreements"), the
holders of  261,273 shares  of Common  Stock (the  "Registrable Securities")  or
their   transferees  are  entitled  to  certain   rights  with  respect  to  the
registration of such shares under the Securities Act. Pursuant to the Investors'
Agreements, subject to  certain exceptions  and limitations, the  holders of  at
least  50% of the Registrable Securities may require, on one occasion during the
four-year period commencing  12 months after  the closing of  the Offering  (the
"Registration  Period"), that the  Company use its best  efforts to register the
Registrable Securities for  public resale. During  the Registration Period,  the
holders of the Registrable Securities may also require the Company (but not more
than  twice  in  any  calendar year)  to  register  all or  a  portion  of their
Registrable Securities on  Form S-3 under  the Securities Act  when use of  such
form  becomes available to the Company;  provided, among other limitations, that
the anticipated  aggregate offering  price, net  of underwriting  discounts  and
commissions,  will  exceed  $500,000  or the  number  of  shares  of Registrable
Securities exceeds 20,000, whichever  has a greater value.  In addition, in  the
event
    
 
                                       55
<PAGE>
the Company elects to register any Common Stock under the Securities Act, either
for  its own account or for the  account of any other stockholders, the Company,
on two such occasions during the Registration Period, is required to notify, and
subject to certain marketing  and other limitations, is  required to include  in
such registration the Registrable Securities of holders requesting registration.
The  holders of 26,126 shares of Common  Stock issuable, after completion of the
Offering,  upon  exercise  of  outstanding  warrants  are  entitled  to  similar
registration rights with respect to the registration of the underlying shares on
a Form S-3 or in the event the Company files a registration statement during the
Registration  Period pursuant  to the  terms of  the warrants.  All registration
expenses of any such registration are to be borne by the Company and all selling
expenses relating to Registrable  Securities are to be  borne by the holders  of
the  securities being registered. See "Certain Transactions -- Relationship with
Interneuron."
 
INTERNEURON CONVERTIBLE DEBENTURE AND PROMISSORY NOTE
 
    On March 31, 1995, the Company issued a convertible debenture in the  amount
of  $387,968 to Interneuron, and procured an additional advance of $28,651 under
such debenture on June 30, 1995. The debenture is convertible immediately  prior
to  the consummation of  this Offering into  a number of  shares of Common Stock
equal to the outstanding  principal amount and any  accrued interest divided  by
the  initial public offering price  of the Common Stock,  plus a cash payment in
lieu of fractional shares.
 
    Interneuron has provided  and continues  to provide  advances to  Progenitor
evidenced  by a promissory note dated March 31, 1996, in the principal amount of
approximately $523,000, as updated from time to time, payable on the earlier  of
five  years  from  the  date  of  the note  or  the  closing  of  this Offering.
Interneuron has  agreed  to  convert  the indebtedness  evidenced  by  the  note
(approximately  $1.2 million as of May  31, 1996), including additional advances
from April 1,  1996 through  the closing of  the Offering  and accrued  interest
thereon,  into shares  of Common  Stock upon  the closing  of the  Offering at a
conversion price  equal  to the  initial  public offering  price.  See  "Certain
Transactions -- Relationship with Interneuron."
 
DELAWARE ANTI-TAKEOVER LAW AND CERTAIN CHARTER PROVISIONS
 
    The  Company is  subject to  the provisions of  Section 203  of the Delaware
General Corporation Law ("DGCL"), an anti-takeover law. In general, the  statute
prohibits  a  publicly-held Delaware  corporation from  engaging in  a "business
combination" with an "interested stockholder" for a period of three years  after
the   date  of  the  transaction  in  which  the  person  became  an  interested
stockholder, unless the business combination is, or the transaction in which the
person became an interested stockholder was, approved in a prescribed manner  or
another  prescribed exemption applies. For purposes  of Section 203, a "business
combination" is  defined  broadly to  include  a  merger, asset  sale  or  other
transaction  resulting in a financial benefit  to the interested stockholder. In
general, an "interested stockholder" is  a person who, together with  affiliates
and  associates, owns (or within the three  years prior to such transaction, did
own) 15% or more of the corporation's voting stock.
 
   
    In addition, certain  provisions of  the Company's  Restated Certificate  of
Incorporation  may have the  effect of preventing,  discouraging or delaying any
change in control  of Progenitor.  The authorization  of undesignated  Preferred
Stock makes it possible for the Board of Directors to issue Preferred Stock with
voting  or other  rights or  preferences that  could impede  the success  of any
attempt to change control of the Company. See "-- Preferred Stock."
    
 
LIMITATION OF LIABILITY
 
    Section 145  ("Section  145") of  the  DGCL provides  a  detailed  statutory
framework covering indemnification of officers and directors against liabilities
and  expenses arising out of legal proceedings brought against them by reason of
their being or having been directors or officers. Section 145 generally provides
that a director  or officer of  a corporation  (i) shall be  indemnified by  the
corporation for all expenses of
 
                                       56
<PAGE>
   
such  legal  proceedings  when he  is  successful  on the  merits,  (ii)  may be
indemnified by the corporation  for the expenses,  judgments, fines and  amounts
paid  in settlement of such proceedings (other  than a derivative suit), even if
he is not successful on the merits, if he acted in good faith and in a manner he
reasonably believed  to be  in  or not  opposed to  the  best interests  of  the
corporation,  and, with  respect to  any criminal  action or  proceeding, had no
reasonable cause  to  believe  his  conduct  was  unlawful,  and  (iii)  may  be
indemnified  by the corporation for the expenses of a derivative suit (a suit by
a stockholder alleging a breach by a director  or officer of a duty owed to  the
corporation),  even if he is  not successful on the merits,  if he acted in good
faith and in a manner he reasonably believed to be in or not opposed to the best
interests of the corporation. No indemnification may be made under clause  (iii)
above,  however, if the director or officer is adjudged liable for negligence or
misconduct in  the  performance of  his  duties  to the  corporation,  unless  a
corporation  determines that, despite such adjudication,  but in view of all the
circumstances, he is entitled to indemnification. The indemnification  described
in  clauses (ii)  and (iii)  above may  be made  only upon  a determination that
indemnification is proper because  the applicable standard  of conduct has  been
met. Such a determination may be made by a majority of a quorum of disinterested
directors,  independent legal counsel, the stockholders  or a court of competent
jurisdiction.
    
 
   
    The Company's Restated  Certificate of Incorporation  will provide that  the
Company  shall indemnify to the  fullest extent permitted by  Section 145, as it
now exists or as  amended, all persons whom  it may indemnify pursuant  thereto.
The  Company intends  to enter  into agreements  to indemnify  its directors and
executive officers, in addition to indemnification provided for in the Company's
charter documents. These agreements,  among other things,  will provide for  the
indemnification  of the Company's  directors and executive  officers for certain
expenses (including attorneys'  fees), judgments, fines  and settlement  amounts
incurred by any such person in any action or proceeding, including any action by
or  in the  right of  the Company, arising  out of  such person's  services as a
director or executive officer of the  Company, any subsidiary of the Company  or
any  other company or enterprise  to which such person  provides services at the
request of the Company  to the fullest extent  permitted by applicable law.  The
Company believes that these provisions and agreements will assist the Company in
attracting  and retaining qualified persons to  serve as directors and executive
officers.
    
 
   
    Section 102(b)(7)  of the  DGCL  permits a  corporation  to provide  in  its
certificate  of incorporation  that a director  of the corporation  shall not be
personally liable to the  corporation or its  stockholders for monetary  damages
for  breach of fiduciary  duty as a  director, except for  liability (i) for any
breach of the director's duty of loyalty to the corporation or its stockholders,
(ii) for  acts or  omissions not  in  good faith  or which  involve  intentional
misconduct  or a knowing violation of law,  (iii) under Section 174 of the DGCL,
or (iv) for any transaction from which the director derived an improper personal
benefit. The Company's  Restated Certificate of  Incorporation will provide  for
the  elimination of  personal liability  of a  director for  breach of fiduciary
duty, as permitted by Section 102(b)(7) of the DGCL.
    
 
    The Underwriting Agreement provides for indemnification by the  Underwriters
under  certain circumstances of  directors, officers and  controlling persons of
the  Company  against  certain  liabilities,  including  liabilities  under  the
Securities Act.
 
    Prior  to  the  closing  of  the Offering,  the  Company  intends  to obtain
liability insurance  insuring  the  Company's  officers  and  directors  against
liabilities that they may incur in such capacities.
 
    The  Investors' Agreements provide for cross-indemnification of stockholders
of the  Company  whose  shares  with  registration  rights  are  included  in  a
registration  under the  Securities Act,  and of  the Company,  its officers and
directors for certain liabilities arising in connection with such registration.
 
TRANSFER AGENT AND REGISTRAR
 
   
    Continental Stock  Transfer  &  Trust  Company has  been  appointed  as  the
transfer agent and registrar for the Company's Common Stock.
    
 
                                       57
<PAGE>
                        SHARES ELIGIBLE FOR FUTURE SALE
 
    Prior  to the Offering, there has not  been any public market for the Common
Stock and there can  be no assurance  that a significant  public market for  the
Common  Stock will  be developed  or be sustained  after the  Offering. Sales of
substantial amounts of Common Stock in the public market after the Offering,  or
the  possibility  of such  sales  occurring, could  adversely  affect prevailing
market prices for the Common Stock or the future ability of the Company to raise
capital through an offering of equity securities.
 
    After the Offering, the  Company will have  outstanding 7,293,819 shares  of
Common  Stock (7,668,819  shares if  the Underwriters'  over-allotment option is
exercised in full). Of these shares, the 2,500,000 shares offered hereby will be
freely tradable in the  public market without  restriction under the  Securities
Act, unless such shares are held by "affiliates" of the Company, as that term is
defined in Rule 144 under the Securities Act.
 
    The  remaining 4,793,819 shares of  Common Stock outstanding upon completion
of the Offering will be "restricted securities" as that term is defined in  Rule
144  ("Restricted Shares").  The Restricted Shares  were issued and  sold by the
Company in private  transactions in reliance  upon exemptions from  registration
under  the Securities Act.  Restricted Shares may  be sold in  the public market
only  if  they  are  registered  or  if  they  qualify  for  an  exemption  from
registration  under the Securities Act, including an exemption under Rule 144 or
701, which are summarized below.
 
   
    Pursuant to "lock-up"  agreements, all of  the Company's executive  officers
and  directors and certain  stockholders, who collectively  hold 771,529 of such
Restricted Shares, have agreed not to  offer, sell, contract to sell, grant  any
option  to purchase or otherwise dispose of any  such shares for a period of 180
days from  the date  of this  Prospectus without  the prior  written consent  of
Vector Securities International, Inc. Interneuron will hold 3,736,017 Restricted
Shares  and has  agreed pursuant to  a lock-up  agreement not to  offer, sell or
otherwise dispose of any of its Restricted Shares for a period of 365 days  from
the  date  of  this  Prospectus  without the  prior  written  consent  of Vector
Securities International, Inc.  The Company  has also  agreed that  it will  not
offer,  sell or otherwise dispose of Common Stock  for a period of 180 days from
the date of this Prospectus, other than pursuant to existing stock option plans,
without the prior written consent of Vector Securities International, Inc.  Upon
termination  of such lock-up agreements,  approximately 321,071 and 3,593,591 of
the Restricted Shares will be eligible for immediate sale beginning 181 days and
366 days, respectively, after the date of this Prospectus, in the public  market
subject  to certain volume, manner of sale  and other limitations under Rule 144
and approximately  385,450  of  such  Restricted Shares  will  be  eligible  for
immediate  sale 181  days after the  date of this  Prospectus without limitation
under Rule 144(k).
    
 
    The Securities and Exchange Commission  has recently proposed amendments  to
Rule  144 and Rule  144(k) that would  permit resale of  restricted shares under
Rule 144 after  a one-year, rather  than a two-year  holding period, subject  to
compliance  with the other  provisions of Rule  144, and would  permit resale of
restricted shares by non-affiliates under  Rule 144(k) after a two-year,  rather
than  a three-year holding  period. Adoption of such  amendments could result in
resale of restricted shares  sooner than would  be the case  under Rule 144  and
Rule 144(k) as currently in effect.
 
    Following the expiration of such lock-up periods, certain shares issued upon
exercise  of options granted by the Company prior to the date of this Prospectus
will also be available for sale in the public market pursuant to Rule 701  under
the  Securities Act. Rule  701 permits resales  of such shares  in reliance upon
Rule 144 but without compliance with certain restrictions, including the holding
period requirement,  imposed under  Rule  144. In  general,  under Rule  144  as
currently  in effect, beginning on             , 1996 (90 days after the date of
this Prospectus),  a  person  (or  persons  whose  shares  of  the  Company  are
aggregated)  who has beneficially owned Restricted Shares for at least two years
(including the holding period of any prior owner who is not an affiliate of  the
Company)  would be entitled  to sell within  any three-month period  a number of
shares that  does  not  exceed the  greater  of  (i) one  percent  of  the  then
outstanding  shares  of Common  Stock  (approximately 72,938  shares immediately
after the Offering),  or (ii) the  average weekly trading  volume of the  Common
Stock  during the four  calendar weeks preceding  the filing of  a Form 144 with
respect  to   such  sale.   Sales   under  Rule   144   are  also   subject   to
 
                                       58
<PAGE>
certain  manner  of sale  and  notice requirements  and  to the  availability of
current public information about the Company. Under Rule 144(k), a person who is
not deemed to have been  an affiliate of the Company  at any time during the  90
days  preceding a sale and who has  beneficially owned the shares proposed to be
sold for at least three years (including  the holding period of any prior  owner
who  is not an affiliate of the Company) is entitled to sell such shares without
complying with  the manner  of sale,  public information,  volume limitation  or
notice provisions of Rule 144.
 
   
    As  of May 31, 1996, options to purchase a total of 606,625 shares of Common
Stock were outstanding under the Company's  stock option plans. Of such  shares,
approximately  508,625 shares are subject to  lock-up agreements for a period of
180 days from the date of this  Prospectus and the remaining 98,000 shares  will
be  available for  sale in  the public  market 90  days after  the date  of this
Prospectus pursuant  to  Rule 701.  As  of May  31,  1996, 661,700  shares  were
available for future option grants under such plans.
    
 
    The  Company intends  to file  after the  effective date  of the  Offering a
Registration Statement on Form S-8 to register an aggregate of 1,268,325  shares
of  Common Stock reserved for issuance under its 1992 Stock Option Plan and 1996
Stock  Incentive  Plan.  Such  Registration  Statement  will  become   effective
automatically  upon filing. Shares  issued under the  foregoing plans, after the
filing of  the Registration  Statement on  Form S-8,  may be  sold in  the  open
market,  subject, in the  case of certain  holders, to the  Rule 144 limitations
applicable to affiliates,  the above-referenced lock-up  agreements and  vesting
restrictions imposed by the Company.
 
    After the closing of the Offering, holders of an aggregate of 261,273 shares
of  Common Stock issued upon the conversion  of Preferred Stock will be entitled
to certain rights  with respect  to the registration  of such  shares under  the
Securities  Act.  In  addition,  the 26,126  shares  issuable  upon  exercise of
outstanding warrants  have  similar  registration rights  during  the  four-year
period commencing 12 months after consummation of the Offering. See "Description
of Capital Stock -- Registration Rights."
 
                                       59
<PAGE>
                                  UNDERWRITING
 
    Subject  to  the terms  and conditions  of  the Underwriting  Agreement, the
underwriters (the  "Underwriters")  named  below,  for  whom  Vector  Securities
International,  Inc.,  Tucker Anthony  Incorporated  and Genesis  Merchant Group
Securities are acting as representatives (the "Representatives"), have severally
agreed to purchase,  subject to  the terms  and conditions  of the  Underwriting
Agreement, and the Company has agreed to sell to the Underwriters, the following
respective number of shares of Common Stock.
 
<TABLE>
<CAPTION>
UNDERWRITERS                                                                           NUMBER OF SHARES
- -------------------------------------------------------------------------------------  -----------------
<S>                                                                                    <C>
Vector Securities International, Inc.................................................
Tucker Anthony Incorporated..........................................................
Genesis Merchant Group Securities....................................................
 
                                                                                             --------
  Total..............................................................................       2,500,000
                                                                                             --------
                                                                                             --------
</TABLE>
 
    The Underwriting Agreement provides that the obligations of the Underwriters
are  subject  to  certain conditions  precedent,  including the  absence  of any
material adverse change  in the Company's  business and the  receipt of  certain
certificates,  opinions  and  letters  from  the  Company  and  its  counsel and
independent auditors. The nature  of the Underwriters'  obligation is such  that
they  are committed to purchase all shares of Common Stock offered hereby if any
of such shares are purchased.
 
    The Underwriters propose to offer the  shares of Common Stock to the  public
at  the offering  price set forth  on the cover  page of this  Prospectus and to
certain dealers at such price  less a concession not in  excess of $         per
share.  The  Underwriters may  allow to  selected dealers  and such  dealers may
reallow a concession  not in  excess of  $          per share  to certain  other
dealers.  After the initial public  offering of the shares  of Common Stock, the
offering price and other selling terms may be changed by the Representatives.
 
    The Company has granted  to the Underwriters an  option, exercisable at  any
time  during the 30-day period after the date of this Prospectus, to purchase up
to an additional 375,000 shares of  Common Stock at the initial public  offering
price  set  forth  on  the  cover page  of  this  Prospectus,  less underwriting
discounts and commissions. The Underwriters may exercise such option solely  for
the  purpose  of  covering  over-allotments,  if  any,  in  connection  with the
Offering. To  the extent  such option  is exercised,  each Underwriter  will  be
obligated,  subject to  certain conditions,  to purchase  approximately the same
percentage of such additional shares as the  number of shares set forth next  to
such  Underwriter's name  in the  preceding table bears  to the  total number of
shares listed in the table.
 
    The offering of the shares is made for delivery when, as and if accepted  by
the  Underwriters and subject  to prior sale and  to withdrawal, cancellation or
modification of the Offering without notice. The Underwriters reserve the  right
to reject an order for the purchase of shares in whole or in part.
 
    At  the request of the Company, the Underwriters have reserved 50,000 shares
for sale to employees, directors and other persons and entities associated  with
the  Company. The number of shares available for sale to the general public will
be reduced to the extent  that the reserved shares  are purchased by persons  or
entities  designated by the Company. Any  reserved shares that are not purchased
by persons  or  entities  designated by  the  Company  will be  offered  by  the
Underwriters  to the general  public on the  same basis as  other shares offered
hereby.
 
    The Company  has  agreed  to  indemnify  the  Underwriters  against  certain
liabilities, including liabilities under the Securities Act, or to contribute to
payments that the Underwriters may be required to make in respect thereof.
 
                                       60
<PAGE>
    The  executive officers, directors and certain  employees of the Company and
other stockholders have  agreed that they  will not, without  the prior  written
consent of Vector Securities International, Inc., offer, sell, contract to sell,
grant any option to purchase or otherwise dispose of any shares of Common Stock,
options or warrants to acquire shares of Common Stock or securities exchangeable
for  or convertible into  shares of Common Stock  for a period  of 180 days (365
days in the case of Interneuron) after the date of this Prospectus. The  Company
has  agreed  that it  will  not, without  the  prior written  consent  of Vector
Securities International, Inc., offer, sell, contract to sell, grant any  option
to  purchase or  otherwise dispose  of any  shares of  Common Stock,  options or
warrants to acquire  shares of Common  Stock or securities  exchangeable for  or
convertible  into shares of Common Stock for a period of 180 days after the date
of this Prospectus, except for securities  issued under its stock option  plans.
See "Shares Eligible for Future Sale."
 
    Prior to the Offering, there has been no public market for the Common Stock.
Consequently,  the initial public offering price  for the shares of Common Stock
included in the Offering will be determined by negotiations between the  Company
and  the Representatives. Among the factors considered in determining such price
will be the history of and prospects for the Company's business and the industry
in which it competes, an assessment of the Company's management and the  present
state  of  the  Company's  development,  its  past  and  present  operations and
financial performance, the  prospects for  future earnings of  the Company,  the
present  state of  the Company's  discovery programs,  the current  state of the
economy in the United States and the  current level of economic activity in  the
industry  in which the Company competes and in related or comparable industries,
and the  current  prevailing  condition in  the  securities  markets,  including
current  market valuations of  publicly traded companies  that are comparable to
the Company.
 
    In February 1996, the Company engaged Vector Securities International,  Inc.
as  its  primary financial  advisor  for a  period  of one  year  with automatic
six-month extensions,  unless terminated  in accordance  with the  terms of  the
agreement,  to provide  certain financial advisory  services to  the Company. As
compensation  for   such   services,   the  Company   paid   Vector   Securities
International,  Inc. a  non-refundable retainer  fee of  $75,000 to  be credited
against  additional   advisory  fees   payable   upon  completion   of   certain
transactions.
 
                                 LEGAL MATTERS
 
    The  validity of the issuance  of the shares of  Common Stock offered hereby
and certain matters relating to the Offering will be passed upon for the Company
by Morrison &  Foerster LLP,  San Francisco, California.  Certain legal  matters
relating  to the Offering will  be passed upon for  the Underwriters by Skadden,
Arps, Slate, Meagher & Flom, Chicago, Illinois.
 
                                    EXPERTS
 
    The financial statements of Progenitor,  Inc. (a Development Stage  Company)
as  of September 30, 1994 and 1995 and for each of the three years in the period
ended September  30,  1995,  and for  the  period  from May  8,  1992  (date  of
inception)  to September 30, 1995, appearing in this Prospectus and Registration
Statement  have  been   audited  by  Coopers   &  Lybrand  L.L.P.,   independent
accountants, as set forth in their report thereon appearing elsewhere herein and
in   this  Registration  Statement,  which  includes  an  explanatory  paragraph
regarding the Company's ability to continue as a going concern, and are included
in reliance upon such report given upon the authority of such firm as experts in
accounting and auditing.
 
    The statements  in  this Prospectus  under  the captions  "Risk  Factors  --
Uncertainty  of  Patents  and  Proprietary  Rights,"  "Business  -- Progenitor's
Functional Genomics Approach," "Business  -- Progenitor's Proprietary  Discovery
Technologies,"  "Business --  Progenitor's Discovery Programs"  and "Business --
Patents and Proprietary Rights"  relating to patent  matters have been  reviewed
and  approved by  Pennie & Edmonds,  New York,  New York, patent  counsel to the
Company, and have been included herein in reliance upon the review and  approval
by such firm as experts in patent law.
 
                                       61
<PAGE>
                             ADDITIONAL INFORMATION
 
    The  Company  has  filed  with the  Securities  and  Exchange  Commission, a
Registration Statement  on Form  S-1, including  amendments thereto,  under  the
Securities  Act with respect to the Common Stock offered hereby. This Prospectus
does not contain all of the information set forth in the Registration  Statement
and  the exhibits  and schedules filed  therewith. For  further information with
respect to the Company and  such Common Stock, reference  is hereby made to  the
Registration  Statement  and  to  the exhibits  and  schedules  filed therewith.
Statements contained in this Prospectus  regarding the contents of any  contract
or other document referred to are not necessarily complete, and in each instance
reference  is made to  the copy of such  contract or other  document filed as an
exhibit to the Registration  Statement, each such  statement being qualified  in
all  respects by such reference. Copies of the Registration Statement, including
the exhibits  and schedules  thereto, may  be inspected  without charge  at  the
principal  office of the Securities and Exchange Commission at 450 Fifth Street,
N.W, Room 1024, Washington, D.C. 20549, and at the following regional offices of
the Securities  and  Exchange  Commission: Midwest  Regional  Office,  500  West
Madison Street, Suite 1400, Chicago, Illinois 60661-2511; and Northeast Regional
Office,  Seven  World Trade  Center, New  York,  New York  10048. Copies  can be
obtained at prescribed rates from the Public Reference Section of the Commission
at 450 Fifth Street, N.W, Room 1024, Washington, D.C. 20549.
 
    The Company  intends  to  distribute  to  its  stockholders  annual  reports
containing  financial statements  audited by its  independent public accountants
and will make available copies of quarterly reports for the first three quarters
of each fiscal year containing unaudited financial information.
 
                                       62
<PAGE>
                         INDEX TO FINANCIAL STATEMENTS
 
<TABLE>
<CAPTION>
                                                                                                               PAGE
                                                                                                             ---------
<S>                                                                                                          <C>
Report of Independent Accountants..........................................................................        F-2
Balance Sheets.............................................................................................        F-3
Statements of Operations...................................................................................        F-4
Statements of Stockholders' Deficit........................................................................        F-5
Statements of Cash Flows...................................................................................        F-6
Notes to the Financial Statements..........................................................................        F-7
</TABLE>
 
                                      F-1
<PAGE>
                       REPORT OF INDEPENDENT ACCOUNTANTS
 
Board of Directors and Stockholders of
Progenitor, Inc.
 
We  have  audited  the  accompanying  balance  sheets  of  Progenitor,  Inc.  (a
Development Stage Company) as  of September 30, 1994  and 1995, and the  related
statements  of operations, stockholders'  deficit, and cash  flows for the years
ended September 30, 1993,  1994 and 1995,  and for the period  from May 8,  1992
(date  of inception) to  September 30, 1995. These  financial statements are the
responsibility of the Company's management. Our responsibility is to express  an
opinion on these financial statements based on our audits.
 
We   conducted  our  audits  in  accordance  with  generally  accepted  auditing
standards. Those standards require that we plan and perform the audit to  obtain
reasonable assurance about whether the financial statements are free of material
misstatement.  An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements. An audit also  includes
assessing  the  accounting principles  used  and significant  estimates  made by
management, as well as evaluating the overall financial statement  presentation.
We believe that our audits provide a reasonable basis for our opinion.
 
In  our opinion, the  financial statements referred to  above present fairly, in
all material respects, the financial position of Progenitor, Inc. (a Development
Stage Company)  as of  September  30, 1994  and 1995,  and  the results  of  its
operations  and its cash flows for the  years ended September 30, 1993, 1994 and
1995, and for the period from May  8, 1992 (date of inception) to September  30,
1995, in conformity with generally accepted accounting principles.
 
The  accompanying financial statements  have been prepared  assuming the Company
will continue  as a  going concern.  As discussed  in Note  1 to  the  financial
statements,  the  Company is  in the  development stage.  The Company's  lack of
revenues and its  need for  additional financing  to fund  its operations  raise
substantial doubt about its ability to continue as a going concern. Management's
plans  in regard to  these matters are  also described in  Note 1. The financial
statements do not include any adjustments that might result from the outcome  of
this uncertainty.
 
                                          COOPERS & LYBRAND L.L.P.
 
Columbus, Ohio
June 5, 1996
 
                                      F-2
<PAGE>
                                PROGENITOR, INC.
                         (A DEVELOPMENT STAGE COMPANY)
                                 BALANCE SHEETS
 
                                     ASSETS
 
<TABLE>
<CAPTION>
                                                                       SEPTEMBER 30,                      PRO FORMA
                                                                  ------------------------   MARCH 31,    MARCH 31,
                                                                     1994         1995         1996         1996
                                                                  -----------  -----------  -----------  -----------
<S>                                                               <C>          <C>          <C>          <C>
                                                                                            (UNAUDITED)  (UNAUDITED)
Current assets:
  Cash and cash equivalents.....................................  $     9,544  $ 1,173,743   $  26,695    $ 176,695
  Accounts receivable...........................................           --      193,898     193,897      193,897
  Accounts receivable -- parent.................................           --      131,600          --           --
  Prepaid expenses and other current assets.....................        3,000       22,618     142,776      142,776
                                                                  -----------  -----------  -----------  -----------
    Total current assets........................................       12,544    1,521,859     363,368      513,368
                                                                  -----------  -----------  -----------  -----------
Property and equipment, at cost:
  Equipment.....................................................      908,788    1,063,602   1,101,622    1,101,622
  Leasehold improvements........................................      121,173           --          --           --
                                                                  -----------  -----------  -----------  -----------
                                                                    1,029,961    1,063,602   1,101,622    1,101,622
    Less accumulated depreciation...............................     (268,030)    (409,120)   (536,281)    (536,281)
                                                                  -----------  -----------  -----------  -----------
                                                                      761,931      654,482     565,341      565,341
Notes receivable officers, net..................................      202,096      218,734     157,888      157,888
                                                                  -----------  -----------  -----------  -----------
    Total assets................................................  $   976,571  $ 2,395,075   $1,086,597   $1,236,597
                                                                  -----------  -----------  -----------  -----------
                                                                  -----------  -----------  -----------  -----------
 
                                       LIABILITIES AND STOCKHOLDERS' DEFICIT
Current liabilities:
  Accounts payable..............................................  $   173,166  $   232,656   $ 133,387    $ 133,387
  Accrued expenses..............................................      679,394    1,343,718     784,748      784,748
  Capital lease obligation -- current...........................      147,907      214,485     245,718      245,718
                                                                  -----------  -----------  -----------  -----------
    Total current liabilities...................................    1,000,467    1,790,859   1,163,853    1,163,853
                                                                  -----------  -----------  -----------  -----------
Note payable -- parent..........................................   10,453,193           --     525,473           --
Convertible debenture -- parent.................................           --      436,740     456,355           --
Accrued interest -- parent......................................      871,585           --          --           --
Capital lease obligation........................................      441,976      268,382     231,736      231,736
                                                                  -----------  -----------  -----------  -----------
      Total liabilities.........................................   12,767,221    2,495,981   2,377,417    1,395,589
                                                                  -----------  -----------  -----------  -----------
Commitments and contingencies
Stockholders' deficit:
  Preferred stock, Series A, $.01 par value: 2,120,000 shares
   authorized; 2,020,496 shares issued and outstanding as of
   September 30, 1995 and March 31, 1996........................           --       20,205      20,205           --
  Preferred stock, Series B, $.01 par value: 880,000 shares
   authorized; 349,000 shares issued and outstanding as of
   September 30, 1995 and March 31, 1996........................           --        3,490       3,490           --
  Common stock, Class A, $.001 par value: 39,000,000 shares
   authorized; 2,568,668, 2,789,271, 2,852,779 and 4,733,612
   (pro forma) shares issued and outstanding as of September 30,
   1993, 1994 and 1995, and March 31, 1996, respectively........        2,569        2,789       2,853        4,734
  Common stock, Class B, $.001 par value: 1,000,000 shares
   authorized; 250,000 shares issued and outstanding as of
   September 30, 1994...........................................          250           --          --           --
  Additional paid-in capital....................................        5,094   14,546,640  14,897,701   16,051,343
  Deficit accumulated during development stage..................  (11,798,563) (14,674,030) (16,215,069) (16,215,069)
                                                                  -----------  -----------  -----------  -----------
    Total stockholders' deficit.................................  (11,790,650)    (100,906) (1,290,820)    (158,992)
                                                                  -----------  -----------  -----------  -----------
    Total liabilities and stockholders' deficit.................  $   976,571  $ 2,395,075   $1,086,597   $1,236,597
                                                                  -----------  -----------  -----------  -----------
                                                                  -----------  -----------  -----------  -----------
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-3
<PAGE>
                                PROGENITOR, INC.
                         (A DEVELOPMENT STAGE COMPANY)
                            STATEMENTS OF OPERATIONS
 
<TABLE>
<CAPTION>
                                                                      MAY 8, 1992                             MAY 8, 1992
                                                                       (DATE OF      SIX MONTHS ENDED MARCH     (DATE OF
                                    YEARS ENDED SEPTEMBER 30,        INCEPTION) TO            31,              INCEPTION)
                              -------------------------------------  SEPTEMBER 30,  ------------------------  TO MARCH 31,
                                 1993         1994         1995          1995          1995         1996          1996
                              -----------  -----------  -----------  -------------  -----------  -----------  ------------
<S>                           <C>          <C>          <C>          <C>            <C>          <C>          <C>
                                                                                    (UNAUDITED)  (UNAUDITED)  (UNAUDITED)
Revenue                       $        --  $        --  $ 2,821,386   $ 2,821,386    $   4,537    $ 911,962   $  3,733,348
Operating expenses:
  Research and
   development..............    3,116,062    4,112,991    4,227,959    12,231,899    1,660,751    1,705,732     13,937,631
  General and
   administrative...........    1,339,086    1,274,896    1,116,652     3,995,433      533,751      690,536      4,685,969
                              -----------  -----------  -----------  -------------  -----------  -----------  ------------
    Total operating
     expenses...............    4,455,148    5,387,887    5,344,611    16,227,332    2,194,502    2,396,268     18,623,600
                              -----------  -----------  -----------  -------------  -----------  -----------  ------------
Interest expense capital
 lease......................           --       44,257       62,945       107,202       34,891       35,292        142,494
Interest expense parent.....      245,391      603,581      289,297     1,160,882      269,175       21,441      1,182,323
                              -----------  -----------  -----------  -------------  -----------  -----------  ------------
    Net loss................  $(4,700,539) $(6,035,725) $(2,875,467)  $(14,674,030) ($2,494,031) ($1,541,039) $(16,215,069)
                              -----------  -----------  -----------  -------------  -----------  -----------  ------------
                              -----------  -----------  -----------  -------------  -----------  -----------  ------------
Pro forma net loss per
 share......................                            $     (0.63)                              $   (0.33)
                                                        -----------                              -----------
                                                        -----------                              -----------
Pro forma weighted-average
 shares outstanding.........                              4,536,481                               4,676,327
                                                        -----------                              -----------
                                                        -----------                              -----------
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-4
<PAGE>
                                PROGENITOR, INC.
                         (A DEVELOPMENT STAGE COMPANY)
                      STATEMENTS OF STOCKHOLDERS' DEFICIT
          FROM MAY 8, 1992 (DATE OF INCEPTION) TO SEPTEMBER 30, 1995,
            AND (UNAUDITED) FOR THE SIX MONTHS ENDED MARCH 31, 1996
<TABLE>
<CAPTION>
                                                               PREFERRED STOCK                            COMMON STOCK
                                                ----------------------------------------------  ---------------------------------
                                                       SERIES A                SERIES B                CLASS A           CLASS B
                                                ----------------------  ----------------------  ----------------------  ---------
                                                 SHARES      AMOUNT      SHARES      AMOUNT      SHARES      AMOUNT      SHARES
                                                ---------  -----------  ---------  -----------  ---------  -----------  ---------
<S>                                             <C>        <C>          <C>        <C>          <C>        <C>          <C>
Balance, May 8, 1992 (inception)
  Issued in May 1992 at $.002 per share.......         --   $      --          --   $      --   2,412,950   $   2,413          --
  Issued in May 1992 at $.001 per share.......         --          --          --          --          --          --     250,000
  Net loss....................................         --          --          --          --          --          --          --
                                                ---------  -----------  ---------  -----------  ---------  -----------  ---------
Balance, September 30, 1992...................         --          --          --          --   2,412,950       2,413     250,000
  Issued in December 1992 and January 1993 at
   $.000 per share under anti-dilution
   provisions.................................         --          --          --          --      13,397          13          --
  Issued in December 1992 and January 1993 at
   $.02 per share.............................         --          --          --          --     216,588         217          --
  Repurchased at $.02 per share...............         --          --          --          --     (74,267)        (74)         --
  Net loss....................................         --          --          --          --          --          --          --
                                                ---------  -----------  ---------  -----------  ---------  -----------  ---------
Balance, September 30, 1993...................         --          --          --          --   2,568,668       2,569     250,000
  Net loss....................................         --          --          --          --          --          --          --
                                                ---------  -----------  ---------  -----------  ---------  -----------  ---------
Balance, September 30, 1994...................         --          --          --          --   2,568,668       2,569     250,000
                                                                                                ---------  -----------  ---------
  Issued preferred stock at $6.25 for
   conversion of debt to equity...............  2,020,496      20,205          --          --          --          --          --
  Conversion of Class B common to Class A
   common under anti-dilution provisions......         --          --          --          --     178,750         179    (250,000)
  Issued in December 1994 at $.000 per share
   under anti-dilution provisions.............         --          --          --          --      40,353          40          --
  Stock options exercised at $.20 per share...         --          --          --          --       1,500           1          --
  Issued preferred stock in December-April at
   $4.47 per share, net of offering costs.....         --          --     349,000       3,490          --          --          --
  Net loss....................................         --          --          --          --          --          --          --
                                                ---------  -----------  ---------  -----------  ---------  -----------  ---------
Balance, September 30, 1995...................  2,020,496      20,205     349,000       3,490   2,789,271       2,789          --
                                                ---------  -----------  ---------  -----------  ---------  -----------  ---------
  Stock options exercised at $.20-$2.00 per
   share......................................         --          --          --          --       5,175           5          --
  Issued common stock in February 1996 at
   $6.00 per share............................         --          --          --          --      58,333          59          --
  Net loss....................................         --          --          --          --          --          --          --
                                                ---------  -----------  ---------  -----------  ---------  -----------  ---------
Balance, March 31, 1996 (Unaudited)...........  2,020,496   $  20,205     349,000   $   3,490   2,852,779   $   2,853          --
                                                ---------  -----------  ---------  -----------  ---------  -----------  ---------
                                                ---------  -----------  ---------  -----------  ---------  -----------  ---------
 
<CAPTION>
 
                                                                            DEFICIT
                                                                          ACCUMULATED
                                                                          DURING THE
                                                              PAID-IN     DEVELOPMENT
                                                  AMOUNT      CAPITAL        STAGE         TOTAL
                                                -----------  ----------  -------------  -----------
<S>                                             <C>          <C>         <C>            <C>
Balance, May 8, 1992 (inception)
  Issued in May 1992 at $.002 per share.......   $      --   $    2,413   $        --   $     4,826
  Issued in May 1992 at $.001 per share.......         250           --            --           250
  Net loss....................................          --           --    (1,062,299)   (1,062,299)
                                                       ---   ----------  -------------  -----------
Balance, September 30, 1992...................         250        2,413    (1,062,299)   (1,057,223)
  Issued in December 1992 and January 1993 at
   $.000 per share under anti-dilution
   provisions.................................          --          (13)           --            --
  Issued in December 1992 and January 1993 at
   $.02 per share.............................          --        4,105            --         4,322
  Repurchased at $.02 per share...............          --       (1,411)           --        (1,485)
  Net loss....................................          --           --    (4,700,539)   (4,700,539)
                                                       ---   ----------  -------------  -----------
Balance, September 30, 1993...................         250        5,094    (5,762,838)   (5,754,925)
  Net loss....................................          --           --    (6,035,725)   (6,035,725)
                                                       ---   ----------  -------------  -----------
Balance, September 30, 1994...................         250        5,094   (11,798,563)  (11,790,650)
                                                       ---   ----------  -------------  -----------
  Issued preferred stock at $6.25 for
   conversion of debt to equity...............          --   12,607,895            --    12,628,100
  Conversion of Class B common to Class A
   common under anti-dilution provisions......        (250)     161,751            --       161,680
  Issued in December 1994 at $.000 per share
   under anti-dilution provisions.............          --      214,960            --       215,000
  Stock options exercised at $.20 per share...          --          299            --           300
  Issued preferred stock in December-April at
   $4.47 per share, net of offering costs.....          --    1,556,641            --     1,560,131
  Net loss....................................          --           --    (2,875,467)   (2,875,467)
                                                       ---   ----------  -------------  -----------
Balance, September 30, 1995...................          --   14,546,640   (14,674,030)     (100,906)
                                                       ---   ----------  -------------  -----------
  Stock options exercised at $.20-$2.00 per
   share......................................          --        1,120            --         1,125
  Issued common stock in February 1996 at
   $6.00 per share............................          --      349,941            --       350,000
  Net loss....................................          --           --    (1,541,039)   (1,541,039)
                                                       ---   ----------  -------------  -----------
Balance, March 31, 1996 (Unaudited)...........   $      --   $14,897,701  $(16,215,069) $(1,290,820)
                                                       ---   ----------  -------------  -----------
                                                       ---   ----------  -------------  -----------
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-5
<PAGE>
                                PROGENITOR, INC.
                         (A DEVELOPMENT STAGE COMPANY)
                            STATEMENTS OF CASH FLOWS
 
<TABLE>
<CAPTION>
                                                                    MAY 8, 1992                             MAY 8, 1992
                                                                     (DATE OF      SIX MONTHS ENDED MARCH     (DATE OF
                                   YEARS ENDED SEPTEMBER 30,       INCEPTION) TO            31,              INCEPTION)
                               ----------------------------------  SEPTEMBER 30,  ------------------------  TO MARCH 31,
                                  1993        1994        1995         1995          1995         1996          1996
                               ----------  ----------  ----------  -------------  -----------  -----------  ------------
<S>                            <C>         <C>         <C>         <C>            <C>          <C>          <C>
                                                                                  (UNAUDITED)  (UNAUDITED)  (UNAUDITED)
Cash flows from operating
 activities:
  Net loss...................  $(4,700,539) $(6,035,725) $(2,875,467)  $(14,674,030) ($2,494,031) ($1,541,039) ($16,215,069)
  Adjustments to reconcile
   net loss to net cash used
   in operating activities:
    Depreciation and
     amortization............     193,539     289,340     262,263       749,668      126,708      141,726       891,394
    Gain on sale of
     equipment...............          --          --          --            --           --      (16,437)      (16,437)
    Noncash expense for anti-
     dilution stock
     issuances...............          --          --     376,680       376,680           --           --       376,680
    Changes in operating
     assets and liabilities:
      Notes receivable
       officers, net.........      16,408     (66,146)    (16,638)     (218,734)     (34,588)      60,846      (157,888)
      Accounts receivable....          --          --    (193,898)     (193,898)          --           --      (193,898)
      Accounts receivable --
       parent................          --          --    (131,600)     (131,600)          --      131,600            --
      Prepaid expenses and
       other current
       assets................      (8,526)      7,000     (19,618)      (22,618)     (28,747)    (120,158)     (142,776)
      Accounts payable.......    (177,065)     59,847      59,490       232,656     (105,835)     (99,269)      133,387
      Accrued expenses.......     279,992     274,529     664,324     1,343,718      108,280     (558,970)      784,748
      Accrued interest --
       parent................     245,391     603,581     261,350     1,132,935      269,175       19,615     1,152,550
                               ----------  ----------  ----------  -------------  -----------  -----------  ------------
    Cash used in operating
     activities..............  (4,150,800) (4,867,574) (1,613,114)  (11,405,223)  (2,159,038)  (1,982,086)  (13,387,309)
                               ----------  ----------  ----------  -------------  -----------  -----------  ------------
Cash flows from investing
 activities:
  Purchase of property and
   equipment.................    (571,419)   (294,623)   (154,814)   (1,404,150)    (119,943)     (36,146)   (1,440,296)
                               ----------  ----------  ----------  -------------  -----------  -----------  ------------
    Cash used in investing
     activities..............    (571,419)   (294,623)   (154,814)   (1,404,150)    (119,943)     (36,146)   (1,440,296)
                               ----------  ----------  ----------  -------------  -----------  -----------  ------------
Cash flows from financing
 activities:
  Proceeds from note payable
   -- parent.................   4,695,371   4,570,771   1,041,972    11,495,165    1,034,147      525,473    12,020,638
  Proceeds from convertible
   debenture -- parent.......          --          --     436,740       436,740      387,968           --       436,740
  Proceeds from issuance of
   stock, net................       2,837          --   1,560,431     1,568,344    1,450,781      351,125     1,919,469
  Proceeds from sale
   leaseback.................          --     662,602      87,771       750,373       87,770      117,325       867,698
  Principal payments on
   capital lease
   obligation................          --     (72,719)   (194,787)     (267,506)     (84,716)    (122,739)     (390,245)
                               ----------  ----------  ----------  -------------  -----------  -----------  ------------
    Cash provided by
     financing activities....   4,698,208   5,160,654   2,932,127    13,983,116    2,875,950      871,184    14,854,300
                               ----------  ----------  ----------  -------------  -----------  -----------  ------------
    Net (decrease) increase
     in cash and cash
     equivalents.............     (24,011)     (1,543)  1,164,199     1,173,743      596,969   (1,147,048)       26,695
Cash and cash equivalents,
 beginning of period.........      35,098      11,087       9,544            --        9,544    1,173,743            --
                               ----------  ----------  ----------  -------------  -----------  -----------  ------------
    Cash and cash
     equivalents, end of
     period..................  $   11,087  $    9,544  $1,173,743   $ 1,173,743    $ 606,513    $  26,695    $   26,695
                               ----------  ----------  ----------  -------------  -----------  -----------  ------------
                               ----------  ----------  ----------  -------------  -----------  -----------  ------------
 
Supplemental disclosure of
 cash flow information:
  Cash paid for interest,
   net.......................  $       --  $   22,937  $   84,265   $   107,202
                               ----------  ----------  ----------  -------------
                               ----------  ----------  ----------  -------------
Supplemental schedule of
 noncash investing and
 financing activities:
</TABLE>
 
    In  1995,  the  parent company  converted  debt of  $11,495,165  and accrued
    interest of $1,132,935  into 2,020,496  shares of Series  A preferred  stock
    (see Note 11).
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-6
<PAGE>
                                PROGENITOR, INC.
                         (A DEVELOPMENT STAGE COMPANY)
                       NOTES TO THE FINANCIAL STATEMENTS
 
1.  ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES:
 
    A.   ORGANIZATION:  Progenitor, Inc.  (the Company), a Delaware Corporation,
is a functional genomics company engaged in the discovery, characterization  and
validation  of novel genes, receptors and  related proteins as therapeutic leads
and targets for the treatment of major diseases.
 
    B.  BASIS OF PRESENTATION:  The accompanying financial statements have  been
prepared  on a going-concern basis, which contemplates the realization of assets
and the  satisfaction of  liabilities  in the  normal  course of  business.  The
financial   statements  do   not  include   any  adjustments   relating  to  the
recoverability and classification of recorded  asset amounts or the amounts  and
classification  of liabilities  that might  be necessary  should the  Company be
unable to continue as a going concern.
 
    During the  year ended  September 30,  1995, the  Company arranged  for  the
financing of its operating activities by borrowing approximately $1,458,000 from
its  parent  company,  Interneuron  Pharmaceuticals,  Inc.  ("Interneuron"),  by
obtaining a $2,500,000 licensing fee from Chiron Corporation ("Chiron"), and  by
raising  approximately $1,560,000 from a private placement offering. Significant
additional research and development activities, clinical testing, and regulatory
approvals must be completed before commercial sales, if any, will commence.  The
Company  is actively  pursuing research  and development  grants and negotiating
equity  and  corporate  partnership  arrangements  to  fund  its  research   and
development activities.
 
    C.     PROPERTY  AND   EQUIPMENT:    Depreciation   is  computed  using  the
straight-line method over the estimated useful lives of the depreciable  assets.
Equipment  leased  under capital  leases  is amortized  using  the straight-line
method over  the  lease term.  Leasehold  improvements are  amortized  over  the
estimated  useful life  of the  asset or  lease term,  whichever is  the shorter
period. Maintenance  and  repairs are  charged  to expense  as  incurred,  while
renewals  and  improvements  are capitalized.  Equipment  includes  $707,972 and
$795,743 of  equipment  under  capital lease  and  accumulated  amortization  of
$83,924 and $298,741 as of September 30, 1994 and 1995, respectively.
 
    D.   REVENUE  RECOGNITION:  The  Company recognizes  revenue under strategic
alliances as certain  agreed upon milestones  are achieved or  license fees  are
earned.
 
    E.   RESEARCH  AND DEVELOPMENT  COSTS:   All costs  related to  research and
development are expensed as incurred.
 
    F.  CASH AND CASH EQUIVALENTS:  For purposes of the statement of cash flows,
cash and  cash  equivalents  consist  of  cash  in  banks,  highly  liquid  debt
instruments  and money market funds with  original maturities of three months or
less.
 
    G.   INTERIM  FINANCIAL  STATEMENTS  (UNAUDITED):    The  interim  financial
statements   reflect  all  adjustments,  consisting  only  of  normal  recurring
accruals, which are, in the opinion of the Company's management, necessary for a
fair presentation of the  financial position and results  of operations for  the
periods  presented.  Revenues  and  expenses  for  any  interim  period  are not
necessarily indicative of results for a full year.
 
    H.  PRO  FORMA PRESENTATION (UNAUDITED):   The pro  forma unaudited  balance
sheet  as  of  March 31,  1996  reflects  (a) the  automatic  conversion  of all
outstanding shares of Preferred Stock into  an aggregate of 1,774,014 shares  of
Common  Stock, (b)  the conversion of  the convertible  debenture and promissory
note held by Interneuron into an aggregate of 81,819 shares of Common Stock  and
(c)  the purchase by the  Ohio University Foundation of  25,000 shares of Common
Stock at a price  of $6.00 per  share pursuant to a  stock purchase right.  Such
conversions will occur upon the closing of the Company's proposed initial public
offering ("IPO") of common stock.
 
                                      F-7
<PAGE>
                                PROGENITOR, INC.
                         (A DEVELOPMENT STAGE COMPANY)
                       NOTES TO THE FINANCIAL STATEMENTS
 
1.  ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES: (CONTINUED)
    I.   PRO FORMA  NET INCOME PER  SHARE (UNAUDITED):   Pro forma unaudited net
income per share is  computed using the  weighted-average number of  outstanding
shares  of common stock and common stock equivalents, assuming conversion of all
outstanding Preferred Stock, the convertible debenture and promissory note  held
by  Interneuron into common stock (as of their original date of issuance), which
will  occur  upon  completion  of  the  Company's  proposed  IPO.  Common  stock
equivalents   are   excluded  from   the  computation   when  their   effect  is
anti-dilutive; however,  pursuant  to the  requirements  of the  Securities  and
Exchange  Commission ("SEC"), common  stock equivalent shares  relating to stock
options and warrants (using the treasury  stock method and an assumed IPO  price
of  $12.00 per  share) issued during  the 12-month  period prior to  the IPO are
included for  all  periods presented  whether  or not  they  are  anti-dilutive.
Historical  earnings per share have not  been presented because such amounts are
not meaningful due to the significant change in the Company's capital  structure
that will occur in connection with the Company's proposed IPO.
 
    J.   RECLASSIFICATIONS:   Certain  reclassifications have  been made  to the
prior year's financial statements to conform to the current-year presentation.
 
    K.  USE OF ESTIMATES:  The preparation of financial statements in conformity
with generally  accepted  accounting  principles  requires  management  to  make
estimates  and  assumptions  that  affect the  reported  amounts  of  assets and
liabilities and disclosure of contingent assets  and liabilities at the date  of
the  financial  statements and  the reported  amounts  of revenues  and expenses
during the reporting period. Actual results could differ from those estimates.
 
    L.   STOCK  SPLIT:   In  May  1996,  the Board  of  Directors  authorized  a
one-for-two  reverse stock split on Class A common shares effective prior to the
effective date of  the proposed IPO.  All references to  Class A common  shares,
underlying  stock options and warrants and per  share data have been restated to
reflect the reverse stock split.
 
2.  ACCRUED EXPENSES:
    Accrued expenses consist of the following:
 
<TABLE>
<CAPTION>
                                                                         1994         1995
                                                                      ----------  ------------
<S>                                                                   <C>         <C>
Sponsored research..................................................  $  494,855  $    438,794
Chiron..............................................................          --       701,296
Other...............................................................     184,539       203,628
                                                                      ----------  ------------
                                                                      $  679,394  $  1,343,718
                                                                      ----------  ------------
                                                                      ----------  ------------
</TABLE>
 
3.  INCOME TAXES:
    No income tax provision or benefit has been provided for federal income  tax
purposes as the Company has incurred losses since inception. As of September 30,
1995,  net deferred  tax assets  totaled approximately  $5,688,000 on  total net
operating loss carryforwards  of approximately  $13,050,000 and  tax credits  of
approximately  $468,000 that  expire on various  dates through 2009.  Due to the
uncertainty surrounding the  realization of  these favorable  tax attributes  in
future tax returns, all of the net deferred tax assets have been fully offset by
a valuation allowance.
 
4.  STOCK OPTIONS AND WARRANTS:
 
    A.   STOCK OPTIONS:  Under the  Company's Stock Option Plan adopted in 1992,
incentive stock  options and  nonqualified  stock options  may be  granted.  The
number of Class A common shares
 
                                      F-8
<PAGE>
                                PROGENITOR, INC.
                         (A DEVELOPMENT STAGE COMPANY)
                       NOTES TO THE FINANCIAL STATEMENTS
 
4.  STOCK OPTIONS AND WARRANTS: (CONTINUED)
authorized  and reserved for  issuance is 500,000.  The outstanding options vest
over a period of three to four years. As of September 30, 1994 and 1995,  32,356
and  81,695  stock options  were exercisable,  respectively. Options  granted to
stockholders with 10% or greater ownership expire after five years.
 
    Stock option activity is summarized below:
 
<TABLE>
<CAPTION>
                                                                       NUMBER OF     OPTION
                                                                        SHARES        PRICE
                                                                      -----------  -----------
<S>                                                                   <C>          <C>
Outstanding at September 30, 1992...................................          --            --
  Granted...........................................................     104,700   $ 0.20-4.00
  Forfeited.........................................................         250          0.20
                                                                      -----------
Outstanding at September 30, 1993...................................     104,450     0.20-4.00
  Granted...........................................................      75,875          4.00
  Forfeited.........................................................       1,700     0.20-4.00
                                                                      -----------
Outstanding at September 30, 1994...................................     178,625     0.20-4.00
  Granted...........................................................     192,250     4.00-6.00
  Forfeited.........................................................      20,472     0.20-4.00
  Exercised.........................................................       1,500          0.20
                                                                      -----------
Outstanding at September 30, 1995...................................     348,903     0.20-6.00
                                                                      -----------
                                                                      -----------
</TABLE>
 
    In September  1995, the  Company  issued 112,500  stock options  to  certain
executives.  These options  vest in September  2002. An  additional 12,500 stock
options were issued that vest upon the achievement of certain milestones.
 
   
    The Company issued 43,250 stock options to certain employees at an  exercise
price  of $6.00 per share. In May 1996,  the Company amended the terms of 80,000
stock options by  changing the vesting  period to three  years and 12,500  stock
options by changing the vesting period to four years.
    
 
    In  December 1995,  the Financial  Accounting Standards  Board (FASB) issued
Statement of Financial  Accounting Standards  ("SFAS") No.  123, ACCOUNTING  FOR
STOCK-BASED   COMPENSATION,  which  changes  the  measurement,  recognition  and
disclosure standards for  stock-based compensation. The  Company will adopt  the
disclosure  requirements of SFAS No. 123 in  fiscal year 1997, but will elect to
continue to measure compensation cost following present accounting rules.
 
    In May 1996, the Company adopted the 1996 Stock Incentive Plan (the "Plan").
The number of common  shares authorized and available  for issuance is  775,000.
Under  the  Plan, incentive  stock  options, nonqualified  stock  options, stock
appreciation rights and stock grants may be granted. In May 1996, 275,000  stock
options  were granted to officers  of the Company at  an exercise price of $9.00
per share.
 
    B.   WARRANTS:   In  June  1995, the  Company  issued to  designees  of  the
Placement  Agent,  which is  an  affiliate of  the  parent company,  warrants to
purchase a total of 34,901 shares  of Series B convertible preferred stock.  The
warrants  were  issued  in  conjunction  with  the  private  placement  offering
discussed in Note  10. The warrants  are exercisable  at a price  of $6.875  per
share  and  expire on  the  earlier of  (i) five  years  from an  initial public
offering of the Company's common stock, or (ii) June 30, 2005. The Company  paid
the Placement Agent approximately $129,000 as its share of placement agent fees.
 
5.  COMMITMENTS:
    The  Company  has  entered  into  various  operating  leases  for furniture,
fixtures, and equipment which expire through the year 1998.
 
                                      F-9
<PAGE>
                                PROGENITOR, INC.
                         (A DEVELOPMENT STAGE COMPANY)
                       NOTES TO THE FINANCIAL STATEMENTS
 
5.  COMMITMENTS: (CONTINUED)
    In April 1994, the  Company entered into a  sale-lease back equipment  lease
financing  agreement with a  leasing company providing  for funding of  up to an
aggregate of $2,200,000 for equipment purchased prior to June 30, 1995. The book
value of the assets leased under this arrangement totaled $795,743, and the  net
asset  value of the equipment totaled  $750,373. During the year ended September
30, 1994, the  Company recorded  and deferred  a loss  on the  leased assets  of
$45,370,  which it is amortizing over the life  of the lease. The lease is being
treated as a capital lease and is guaranteed by Interneuron.
 
    In November 1994, the Company entered  into a one-year lease for  laboratory
and  administrative space that expires in  December 1995. The lease provides for
monthly rental payments of approximately  $10,900. The Company has extended  the
lease  through 1996. The Company has the option  to extend the lease on a yearly
basis for 1997.  The minimum rental  commitments under these  agreements are  as
follows:
 
<TABLE>
<CAPTION>
                                                                     OPERATING   CAPITAL LEASE
YEARS ENDING SEPTEMBER 30,                                             LEASES     OBLIGATION
- -------------------------------------------------------------------  ----------  -------------
<S>                                                                  <C>         <C>
1996...............................................................  $  174,679   $   258,699
1997...............................................................      16,138       258,699
1998...............................................................      11,783        29,466
1999...............................................................      10,331            --
2000...............................................................       3,444            --
                                                                     ----------  -------------
Total lease payments...............................................  $  216,375       546,864
                                                                     ----------
                                                                     ----------
Less amount representing interest..................................                   (63,997)
                                                                                 -------------
Present value of future lease payments.............................                   482,867
Less current portion...............................................                  (214,485)
                                                                                 -------------
Noncurrent portion of capital lease obligation.....................               $   268,382
                                                                                 -------------
                                                                                 -------------
</TABLE>
 
    Rent  expense approximated $97,000,  $140,000 and $186,000  during the years
ended September 30,  1993, 1994  and 1995,  respectively, and  $514,000 for  the
period May 8, 1992 (date of inception) through September 30, 1995.
 
6.  RELATED-PARTY TRANSACTIONS:
    Under  employment agreements  with certain executives,  the Company advanced
loans to assist in purchasing  new homes. As of  September 30, 1995, there  were
loans to three executives for a total of $359,744. The first loan of $100,796 is
interest-free,  with  $60,796  due  upon  the  earlier  of  April  1997  or  the
termination of the officer's employment. The remaining balance is to be forgiven
upon the achievement of specified milestones. The second loan of $182,500  bears
interest  at 7% per annum, with $142,500 due upon the earlier of the sale of the
officer's existing home, June 1997, or termination of the officer's  employment.
The  remaining  balance is  to  be forgiven  upon  the achievement  of specified
milestones. During 1995, loans totaling $76,448 were made to a third  executive,
$21,448  of  which  is non-interest-bearing  and  was  repaid in  May  1996. The
remaining loans bear interest at 9% per annum, with $15,000 due upon the earlier
of March 1999, or  the termination of the  officer's employment. The balance  of
$40,000 is to be forgiven upon the achievement of specified milestones.
 
    The  Company has recorded $81,200 and $141,010  as of September 30, 1994 and
1995, respectively,  as  a  note  receivable  reserve  in  anticipation  of  the
potential forgiveness of certain loan amounts.
 
                                      F-10
<PAGE>
                                PROGENITOR, INC.
                         (A DEVELOPMENT STAGE COMPANY)
                       NOTES TO THE FINANCIAL STATEMENTS
 
7.  CONSULTING AGREEMENTS:
    The  Company has entered into various consulting agreements which range from
one to three  years and  are subject  to renewals,  whereby outside  consultants
provide  scientific advice and administrative  services to the Company. Payments
to consultants made during 1993, 1994 and 1995, totaled approximately  $203,500,
$309,000  and $243,000,  respectively, and $914,000  for the period  May 8, 1992
(date of inception) through September 30, 1995. Of these amounts,  approximately
$181,000,  $190,000 and $177,400 represented payments to certain stockholders in
1993, 1994 and 1995, respectively, and $707,400 for the period May 8, 1992 (date
of inception) through September 30, 1995.
 
8.  LICENSE AND RESEARCH AGREEMENTS:
    The Company  entered  into a  license  agreement and  a  sponsored  research
agreement  with Ohio  University in  January 1992,  certain terms  of which were
amended in October 1993. The license agreement grants the Company the  exclusive
worldwide  license to patent and other rights to yolk sac stem cells and related
technologies in exchange for  royalties based on  sales. The research  agreement
requires  the Company to  fund specified minimum levels  of research and related
expenses, as well as any additional costs approved in advance by the Company.
 
   
    In addition,  the Company  agreed to  issue 5%  of its  equity to  The  Ohio
University  Foundation and agreed to preserve this percentage ownership position
until the parent  company's total investment  in the Company  is at least  $10.0
million  or the date of an IPO by  the Company. The $10.0 million investment was
achieved during 1995, thus the percentage ownership position no longer needs  to
be  preserved. Until an  initial public offering of  the Company is consummated,
The Ohio University Foundation was entitled to increase its interest to 6.25% by
purchasing additional equity at a  price equal to 50%  of the offering price  of
common stock in any such initial public offering. This provision was canceled in
February 1996, at which time The Ohio University Foundation entered into a stock
purchase  agreement  with  the Company  pursuant  to which  The  Ohio University
Foundation purchased  58,333 shares  of  common stock  for $350,000  ($6.00  per
share).  If the IPO price is less  than $12.00 per share, additional shares will
be issued until The Ohio University Foundation has paid a maximum of 50% of  the
IPO  price.  Additionally,  a  stock  purchase  right  was  issued  to  The Ohio
University Foundation to purchase  25,000 shares of the  common stock at 50%  of
the IPO price.
    
 
   
    The  license  agreement also  contains certain  requirements related  to the
management and  operation  of  the  Company, including  the  nomination  of  two
designees  of The Ohio  University Foundation to  the Board of  Directors of the
Company. The Castle  Group, Ltd.  ("Castle"), which  is controlled  by a  former
director  of  the  Company  and  a  principal  stockholder  of  Interneuron, has
unconditionally guaranteed to Ohio University  the performance of the  Company's
obligations  under the license agreement  until the earlier of  five years or an
initial public offering by the Company.  Certain employees of Castle own  common
stock of the Company.
    
 
    In  April 1993, the  Company entered into  a second license  agreement and a
sponsored research agreement with Ohio University pursuant to which the  Company
agreed to fund research relating to the T7T7 gene delivery system, developing an
active  cell membrane transport system. The license agreement grants the Company
the exclusive worldwide license to all patent and other rights derived from this
and related technologies in exchange for royalties based on sales.
 
    In February 1994, the Company entered  into a license agreement with  Albert
Einstein  College  of Medicine  of Yeshiva  University ("AECOM").  The agreement
grants the  Company the  exclusive worldwide  license to  all patent  and  other
rights  from research  done on  retroviral vectors  by AECOM  in exchange  for a
license fee and royalties based on sales.
 
                                      F-11
<PAGE>
                                PROGENITOR, INC.
                         (A DEVELOPMENT STAGE COMPANY)
                       NOTES TO THE FINANCIAL STATEMENTS
 
8.  LICENSE AND RESEARCH AGREEMENTS: (CONTINUED)
    In September  1994,  the  Company  entered into  a  license  agreement  with
Wisconsin  Alumni Research Foundation ("WARF"). The agreement grants the Company
a nonexclusive license to  certain patents developed by  WARF in exchange for  a
license fee, maintenance fees, and royalties based on sales.
 
    In  November  1994, the  Company  was awarded  a  competitive grant  of $2.0
million through the Advanced Technology  Program ("ATP") of the U.S.  Department
of Commerce. The funds will be received over a three-year period commencing June
1, 1995.
 
    In  March  1995,  the  Company  entered  into  a  license  and collaboration
agreement with Chiron. As required by the agreement, an initial cash payment  of
$2.5  million was paid by  Chiron to the Company in  April 1995. The Company has
committed to reimburse Chiron the start-up manufacturing costs incurred  related
to this agreement up to $750,000. Chiron paid $500,000 to the Company in January
1996,  for  continued  research funding.  The  agreement also  calls  for future
payments contingent upon the achievement of certain milestones.
 
    In May  1995, the  Company entered  into a  sponsored research  and  license
agreement  with  Novo Nordisk,  through its  subsidiary, ZymoGenetics,  Inc. The
agreement calls  for  research and  license  fees to  be  paid to  the  Company,
contingent upon certain conditions and the meeting of certain milestones.
 
    Additionally,  the  Company  has  entered  into  various  sponsored research
agreements with varying  terms up to  two years in  length. The total  sponsored
research  expense  was  $882,217,  $890,000 and  $601,103  for  the  years ended
September 30, 1993, 1994 and 1995,  respectively, and $2,690,680 for the  period
from  May 8, 1992  (date of inception)  through September 30,  1995. Payments to
Ohio University for sponsored research totaled $485,480, $245,888 and  $353,527,
for  the  years  ended September  30,  1993,  1994 and  1995,  respectively, and
$1,281,132 for the period May 8, 1992 (date of inception) through September  30,
1995.  Amounts owed to Ohio University  for sponsored research were $424,401 and
$215,600 at September 30, 1994 and 1995, respectively. In addition, at September
30, 1995, the Company had commitments  to fund additional sponsored research  of
approximately $824,000, including a commitment of $52,390 to Ohio University.
 
9.  COMMON STOCK:
    The  Company is authorized to  issue two classes of  shares of common stock,
designated Class A and Class B. Shares of the Company's Class B common stock are
convertible, at any time  at the option  of the holder, into  shares of Class  A
common  stock. The  conversion ratio is  subject to adjustment  based on several
factors, including the issuance of additional Class A shares.
 
    Holders of Class B  shares are entitled to  pro rata dividend,  liquidation,
and  voting rights based on the number of Class A shares into which such Class B
shares are convertible. Class  B shares are automatically  converted to Class  A
shares upon the receipt by the Company of capital contributions of $10.0 million
in  aggregate amount from the  date of incorporation. When  this was achieved in
1995, all Class B shares were converted  into a total of 357,500 Class A  common
shares.
 
10. PREFERRED STOCK:
    In   December  1994,   the  Company's   Board  of   Directors  approved  the
authorization of 2,120,000  shares of Series  A and 880,000  shares of Series  B
preferred  stock. These preferred shares are  convertible into shares of Class A
common stock and have preferential rights in terms of dividends and  liquidation
over  common stock. Shares  of preferred stock  have voting rights  equal to the
number of shares of their common stock equivalent.
 
                                      F-12
<PAGE>
                                PROGENITOR, INC.
                         (A DEVELOPMENT STAGE COMPANY)
                       NOTES TO THE FINANCIAL STATEMENTS
 
10. PREFERRED STOCK: (CONTINUED)
    Shares of  Series A  preferred stock  are convertible,  at any  time at  the
option  of  the  holder,  into  shares of  Class  A  common  stock.  The initial
conversion ratio is based on  a Series A price  of $6.25, subject to  adjustment
based  on several factors. Series A preferred shares are automatically converted
upon a qualified public offering.
 
    Through July 7,  1995, the  Company has issued  349,000 shares  of Series  B
preferred stock in connection with private placements. The private placement was
a  sale  of units,  each unit  consisting of  shares of  preferred stock  of the
Company, shares  of  preferred  stock  of  another  subsidiary  of  Interneuron,
Transcell  Technologies, Inc., and a put  protection right from Interneuron. The
put protection right provides that on the third anniversary of the final closing
date of the private placement, the owner has the right to sell to Interneuron  a
percentage  of the preferred stock of the Company that is deemed to be illiquid,
as defined in the agreement. The Company received approximately $1,560,000,  net
of  offering costs,  as its  share of the  proceeds from  the private placement.
Shares of Series B preferred stock are convertible, at any time at the option of
the holder, into shares of Class A common stock. The initial conversion ratio is
based on a  Series B  price of  $6.25, subject  to adjustment  based on  several
factors.  Series B preferred shares are automatically converted upon a qualified
public offering.
 
    Shares of authorized common stock have been reserved for the exercise of all
convertible preferred stock outstanding.
 
11. NOTE PAYABLE TO THE PARENT COMPANY:
    The note payable to the parent company, Interneuron, bore interest at a rate
of 1% over the prime lending rate (7  3/4% prime plus 1% at September 30,  1994)
and was payable on demand. Periodic advances were made available under this note
at  the discretion of Interneuron. In  December 1994, the outstanding balance on
the Note Payable -- parent of $11,495,165 and accrued interest of $1,132,935 was
converted into 2,020,496 shares of Series A preferred stock.
 
    In March 1996, the  Company entered into a  promissory note with the  parent
company,  bearing interest at a rate of 1% over the prime lending rate. The note
is due on  the earlier of  March 31, 2001  or the closing  of an initial  public
offering.
 
    Since the inception of the Company, Interneuron has paid for certain Company
expenses which were reimbursed by the Company at cost.
 
12. CONVERTIBLE DEBENTURE-PARENT:
    In  March 1995, the  Company entered into  a convertible debenture agreement
with IPI, at a rate  of 1% over the prime  lending rate. The prime lending  rate
was  8.75%  as of  September 30,  1995. Principal  and interest  are due  at the
earlier of five years  from the final  closing date or  upon a qualified  public
offering  as defined in the agreement. The debenture is convertible, at any time
at the option of the holder, into shares of Class A common stock. The conversion
price is equal to the fair market value  of the common stock at the time of  the
conversion.  The debenture  is automatically  converted upon  a qualified public
offering.
 
13. EMPLOYEE BENEFITS:
    Employees of  the Company  are eligible  to participate  in the  Interneuron
Pharmaceuticals,  Inc. 401(k)  Savings Plan  under which  employees may  defer a
portion of  their  annual  compensation. Company  contributions  to  the  401(k)
Savings  Plan may be made on a discretionary basis. As of September 30, 1995, no
Company contributions have been made.
 
                                      F-13
<PAGE>
   
[Two  color photographs showing the following: 1. The location of the human B219
leptin receptor gene  on human  chromosome lp32; and  2. Staining  of the  Del-1
protein  in the endothelial cells  of blood vessels in a  human tumor grown in a
mouse.]
    
<PAGE>
- --------------------------------------------
                                    --------------------------------------------
- --------------------------------------------
                                    --------------------------------------------
 
    NO  DEALER,  SALES  REPRESENTATIVE  OR ANY  OTHER  PERSON  IS  AUTHORIZED IN
CONNECTION WITH ANY OFFERING MADE HEREBY TO GIVE ANY INFORMATION OR TO MAKE  ANY
REPRESENTATION  NOT CONTAINED HEREIN AND, IF  GIVEN OR MADE, SUCH INFORMATION OR
REPRESENTATION MUST NOT BE RELIED UPON AS HAVING BEEN AUTHORIZED BY THE  COMPANY
OR  THE UNDERWRITERS. THIS PROSPECTUS DOES NOT  CONSTITUTE AN OFFER TO SELL OR A
SOLICITATION OF AN OFFER TO BUY ANY SECURITY OTHER THAN THE COMMON STOCK OFFERED
HEREBY, NOR DOES IT CONSTITUTE AN OFFER TO SELL OR A SOLICITATION OF AN OFFER TO
BUY ANY OF THE COMMON STOCK OFFERED HEREBY TO ANY PERSON IN ANY JURISDICTION  IN
WHICH IT IS UNLAWFUL TO MAKE SUCH AN OFFER OR SOLICITATION. NEITHER THE DELIVERY
OF  THIS PROSPECTUS  NOR ANY SALE  MADE HEREUNDER SHALL  UNDER ANY CIRCUMSTANCES
CREATE ANY IMPLICATION  THAT THERE  HAS BEEN  NO CHANGE  IN THE  AFFAIRS OF  THE
COMPANY  SINCE  THE DATE  HEREOF  OR THAT  THE  INFORMATION CONTAINED  HEREIN IS
CORRECT AS OF ANY DATE SUBSEQUENT TO THE DATE HEREOF.
 
                            ------------------------
 
                               TABLE OF CONTENTS
 
   
<TABLE>
<CAPTION>
                                                     PAGE
                                                   ---------
<S>                                                <C>
Prospectus Summary...............................          3
Risk Factors.....................................          5
Use of Proceeds..................................         17
Dividend Policy..................................         17
Capitalization...................................         18
Dilution.........................................         19
Selected Financial Data..........................         20
Management's Discussion and Analysis of Financial
  Condition and Results of Operations............         21
Business.........................................         24
Management.......................................         40
Certain Transactions.............................         48
Principal Stockholders...........................         53
Description of Capital Stock.....................         54
Shares Eligible for Future Sale..................         58
Underwriting.....................................         60
Legal Matters....................................         61
Experts..........................................         61
Additional Information...........................         62
Index to Financial Statements....................        F-1
</TABLE>
    
 
                            ------------------------
 
    UNTIL               , 1996 (25 DAYS AFTER THE DATE OF THIS PROSPECTUS),  ALL
DEALERS EFFECTING TRANSACTIONS IN THE COMMON STOCK, WHETHER OR NOT PARTICIPATING
IN  THIS  DISTRIBUTION, MAY  BE REQUIRED  TO  DELIVER A  PROSPECTUS. THIS  IS IN
ADDITION TO THE  OBLIGATION OF DEALERS  TO DELIVER A  PROSPECTUS WHEN ACTING  AS
UNDERWRITERS AND WITH RESPECT TO THEIR UNSOLD ALLOTMENTS OR SUBSCRIPTIONS.
 
                                2,500,000 SHARES
   
                                     [LOGO]
    
                                  COMMON STOCK
 
                              -------------------
 
                                   PROSPECTUS
 
                              -------------------
 
                     Vector Securities International, Inc.
 
                                 Tucker Anthony
                                  Incorporated
 
                             Genesis Merchant Group
                                    Securities
 
                                           , 1996
 
- --------------------------------------------
                                    --------------------------------------------
- --------------------------------------------
                                    --------------------------------------------
<PAGE>
                                    PART II
                     INFORMATION NOT REQUIRED IN PROSPECTUS
 
ITEM 13.  OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION
 
    The  following  table  sets  forth  all  expenses,  other  than underwriting
discounts and commissions, payable by the Registrant in connection with the sale
of the Common Stock being registered. All the amounts shown are estimates except
for the SEC registration fee, the NASD filing fee and the Nasdaq listing fee.
 
<TABLE>
<S>                                                                 <C>
SEC Registration Fee..............................................  $  12,888
NASD Filing Fee...................................................      4,238
Nasdaq National Market Listing Fee................................     38,971
Printing and engraving expenses...................................      *
Legal fees and expenses...........................................      *
Accounting fees and expenses......................................      *
Blue sky fees and expenses........................................     15,000
Transfer agent and registrar fees.................................      *
Miscellaneous.....................................................      *
                                                                    ---------
    Total.........................................................  $ 850,000
                                                                    ---------
                                                                    ---------
</TABLE>
 
- --------------
*   To be supplied by amendment.
 
ITEM 14.  INDEMNIFICATION OF OFFICERS AND DIRECTORS
 
    Section 145 ("Section 145") of the Delaware General Corporation Law ("DGCL")
provides a detailed statutory framework covering indemnification of officers and
directors against  liabilities and  expenses arising  out of  legal  proceedings
brought  against  them by  reason of  their  being or  having been  directors or
officers. Section  145  generally provides  that  a  director or  officer  of  a
corporation (i) shall be indemnified by the corporation for all expenses of such
legal  proceedings when he is successful on  the merits, (ii) may be indemnified
by the  corporation for  the  expenses, judgments,  fines  and amounts  paid  in
settlement of such proceedings (other than a derivative suit), even if he is not
successful  on  the  merits, if  he  acted in  good  faith  and in  a  manner he
reasonably believed  to be  in  or not  opposed to  the  best interests  of  the
corporation,  and, with  respect to  any criminal  action or  proceeding, had no
reasonable cause  to  believe  his  conduct  was  unlawful,  and  (iii)  may  be
indemnified  by the corporation for the expenses of a derivative suit (a suit by
a stockholder alleging a breach by a director  or officer of a duty owed to  the
corporation),  even if he is  not successful on the merits,  if he acted in good
faith and in a manner he reasonably believed to be in or not opposed to the best
interests of the corporation. No indemnification may be made under clause  (iii)
above,  however, if the director or officer is adjudged liable for negligence or
misconduct in  the  performance of  his  duties  to the  corporation,  unless  a
corporation  determines that, despite such adjudication,  but in view of all the
circumstances, he is entitled to indemnification. The indemnification  described
in  clauses (ii)  and (iii)  above may  be made  only upon  a determination that
indemnification is proper because  the applicable standard  of conduct has  been
met. Such a determination may be made by a majority of a quorum of disinterested
directors,  independent legal counsel, the stockholders  or a court of competent
jurisdiction. The  Company's  Certificate  of Incorporation  provides  that  the
Company  shall indemnify to the  fullest extent permitted by  Section 145, as it
now exists or as amended, all persons whom it may indemnify pursuant thereto.
 
    Section 102(b)(7)  of the  DGCL  permits a  corporation  to provide  in  its
Certificate  of Incorporation  that a director  of the corporation  shall not be
personally liable to the  corporation or its  stockholders for monetary  damages
for  breach of fiduciary  duty as a  director, except for  liability (i) for any
breach of the director's duty of loyalty to the corporation or its stockholders,
(ii) for  acts or  omissions not  in  good faith  or which  involve  intentional
misconduct  or  a knowing  violation  of law,  (iii)  under Section  174  of the
 
                                      II-1
<PAGE>
DGCL, or (iv) for  any transaction from which  the director derived an  improper
personal  benefit. The Company's  Certificate of Incorporation  provides for the
elimination of personal liability of a director for breach of fiduciary duty, as
permitted by Section 102(b)(7) of the DGCL.
 
   
    Section  of the Form of Underwriting  Agreement, to be filed as Exhibit  1.1
hereto, contains certain provisions relating to indemnification.
    
 
    Prior  to  the  closing  of  the Offering,  the  Company  intends  to obtain
liability insurance  insuring  the  Company's  officers  and  directors  against
liabilities that they may incur in such capacities.
 
   
    The  Company intends to enter into agreements to indemnify its directors and
executive officers, in addition to indemnification provided for in the Company's
charter documents. These agreements,  among other things,  will provide for  the
indemnification  of the Company's  directors and executive  officers for certain
expenses (including attorneys'  fees), judgments, fines  and settlement  amounts
incurred by any such person in any action or proceeding, including any action by
or  in the  right of  the Company, arising  out of  such person's  services as a
director or executive officer of the  Company, any subsidiary of the Company  or
any  other company or enterprise  to which such person  provides services at the
request of the Company  to the fullest extent  permitted by applicable law.  The
Company believes that these provisions and agreements will assist the Company in
attracting  and retaining qualified persons to  serve as directors and executive
officers.
    
 
    The Investors' Agreements provide for cross-indemnification of  stockholders
of  the  Company  whose  shares  with  registration  rights  are  included  in a
registration under the  Securities Act,  and of  the Company,  its officers  and
directors for certain liabilities arising in connection with such registration.
 
    See also the undertakings set out in response to Item 17 herein.
 
ITEM 15.  RECENT SALES OF UNREGISTERED SECURITIES.
 
    Since  January  1,  1993, the  Company  has  issued and  sold  the following
unregistered securities:
 
    (1) In 1993, the Company (a) sold 82,907 shares of Common Stock to Dr. Given
       for $.02 per share pursuant to the terms of his employment agreement, (b)
       issued 11,400 shares of  Common Stock to  The Ohio University  Foundation
       without  additional consideration pursuant to certain antidilution rights
       contained in a stock purchase agreement with the Company and (c) issued a
       certificate for 14,854 shares of Common  Stock to Dr. Cooper in  exchange
       for  certificates  for  89,121  shares  of  Common  Stock  pursuant  to a
       repurchase of  Common Stock  in connection  with the  termination of  Dr.
       Cooper's employment agreement with the Company.
 
    (2)  In 1994, the Company  (a) issued 178,750 shares  of Common Stock to Dr.
       Thomas Wagner upon the conversion of  the shares of Class B Common  Stock
       held  by Dr. Wagner and  (b) issued 40,353 shares  of Common Stock to The
       Ohio University Foundation without  additional consideration pursuant  to
       certain  antidilution rights contained in a stock purchase agreement with
       the Company.
 
    (3) Between December  1994 and  July 1995, the  Company issued  and sold  an
       aggregate  of  349,000  shares of  Series  B Preferred  Stock  to certain
       persons and  entities  for  $4.48  per share.  In  connection  with  such
       transaction,  the Company  issued warrants  to purchase  22,627 shares of
       Series B Preferred  Stock to  designees of Paramount  Capital, Inc.,  the
       placement  agent for  such transaction,  and warrants  to purchase 12,274
       shares of Series  B Preferred  Stock to designees  of D.H.  Blair &  Co.,
       Inc.,  selected dealer for  such transaction, pursuant  to rights of such
       entities under agreements with the Company.
 
    (4) In December 1994, upon the initial  closing of the issuance and sale  of
       Series  B Preferred Stock  described in paragraph  (3) above, in exchange
       for the cancellation of  an aggregate of  approximately $12.6 million  of
       debt  owed by  the Company  to Interneuron,  the Company  issued and sold
       2,020,496 shares of Series A Preferred Stock to Interneuron for $6.25 per
       share.
 
                                      II-2
<PAGE>
    (5) In 1996, the  Company issued (a)  58,333 shares of  Common Stock to  The
       Ohio  University Foundation pursuant to  a Stock Purchase Agreement dated
       as of February 26, 1996, for $6.00  per share, (b) issued and sold  6,625
       shares  of Common Stock  for $0.20 per share  to certain former employees
       pursuant to the exercise  of stock options granted  under the 1992  Stock
       Option  Plan and (c) issued and sold  50 shares of Common Stock for $2.00
       per share to a former employee pursuant to the exercise of stock  options
       granted under the 1992 Stock Option Plan.
 
    (6)  Since January 1, 1993, the  Company granted stock options to employees,
       consultants,  directors,  officers  and  affiliates  of  the  Company  as
       described  below. From  February 1 to  June 1, 1993,  the Company granted
       stock options under the 1992 Stock  Option Plan covering an aggregate  of
       82,450 shares of Common Stock at an exercise price of $0.20 per share. On
       June  21, 1993,  the Company granted  stock options under  the 1992 Stock
       Option Plan covering an aggregate of 14,250 shares of Common Stock at  an
       exercise  price of  $2.00 per  share. From June  2, 1993  to December 31,
       1994, the Company granted stock options under the 1992 Stock Option  Plan
       covering  an aggregate  of 84,375 shares  of Common Stock  at an exercise
       price of $4.00 per share.  From March 1, 1995  to February 21, 1996,  the
       Company  granted stock options under the  1992 Stock Option Plan covering
       an aggregate of 235,000  shares of Common Stock  at an exercise price  of
       $6.00 per share. On May 13, 1996, the Company granted stock options under
       the  1996 Stock Incentive Plan covering an aggregate of 275,000 shares of
       Common Stock at an exercise price of $9.00 per share.
 
    The sales and  issuances of Common  Stock in the  transactions described  in
paragraphs  (1), (2) and (5) above other  than pursuant to the exercise of stock
options were deemed  to be  exempt from  registration under  the Securities  Act
pursuant to Section 4(2) thereof.
 
    The  issuance and sale of  the Series B Preferred  Stock in the transactions
described in paragraph (3) were deemed to be exempt from registration under  the
Securities  Act pursuant to Section 4(2) of the Securities Act and/or Regulation
D promulgated thereunder.
 
    The issuance of the warrants in the transactions described in paragraph  (3)
was  deemed to be exempt from registration  under the Securities Act pursuant to
Section 4(2) thereof.
 
    The issuance and  sale of the  Series A Preferred  Stock in the  transaction
described  in paragraph (4) were deemed to be exempt from registration under the
Securities Act pursuant to Section 4(2) thereof.
 
    The issuances and sales  of Common Stock pursuant  to the exercise of  stock
options  described in paragraph  (5) were deemed to  be exempt from registration
under the Securities Act by virtue  of Rule 701 promulgated thereunder, or  were
deemed to be exempt pursuant to Section 4(2) thereof.
 
    With  respect  to the  grant of  stock options  described in  paragraph (6),
exemption from registration  under the  Securities Act was  unnecessary in  that
none  of such transactions involved a "sale"  of securities as such term is used
in Section 2(3) of the Securities Act.
 
ITEM 16.  EXHIBITS AND FINANCIAL STATEMENT SCHEDULES.
 
    (A) EXHIBITS.
 
   
<TABLE>
<C>        <S>
     +1.1  Form of Underwriting Agreement.
      3.1  Form of Amended and Restated Certificate of Incorporation of the Company.
      3.2  Amended and Restated Bylaws of the Company.
     +4.1  Specimen Stock Certificate of the Company.
      4.2  Reference is made to Exhibits 3.1 and 3.2.
    **5.1  Opinion of Morrison & Foerster LLP.
</TABLE>
    
 
                                      II-3
<PAGE>
   
<TABLE>
<C>        <S>
     10.1  Form of  Indemnification  Agreement entered  into  between the  Company  and  its
           directors and executive officers.
   **10.2  The Company's 1992 Stock Option Plan.
   **10.3  Form of Incentive Stock Option Agreement under the 1992 Stock Option Plan.
   **10.4  Form of Non-Qualified Stock Option Agreement under the 1992 Stock Option Plan.
     10.5  The Company's 1996 Stock Incentive Plan and form of Stock Option Agreement.
   **10.6  Form  of Investors' Rights Agreement, entered into among the Company, Interneuron
           Pharmaceuticals, Inc.,  Transcell  Technologies, Inc.,  and  the holders  of  the
           Company's Preferred Stock, Series B.
 */**10.7  License  Agreement, dated as of  January 28, 1992, by  and between Scimark Corp.,
           The Castle Group Ltd. and Ohio University, as amended October 15, 1993.
 */**10.8  Sponsored Research  Agreement, dated  January 31,  1992, by  and between  Scimark
           Corp.  and  Ohio University,  as  amended October  15,  1993, February  16, 1994,
           November 16, 1994 and November 22, 1995.
 */**10.9  License Agreement, dated as of April 1, 1993, by and between the Company and Ohio
           University.
*/**10.10  Sponsored Research Agreement, dated April 1, 1993, by and between the Company and
           Ohio University, as amended August 7, 1995 and November 22, 1995.
  **10.11  License Agreement, dated  as of  June 8,  1994, by  and between  the Company  and
           Associated Universities, Inc.
*/**10.12  Standard  License Agreement, dated  as of September  1, 1994, by  and between the
           Company and the Wisconsin Alumni Research Foundation, as amended June 2, 1995.
*/**10.13  License and Collaboration Agreement, dated as  of March 31, 1995, by and  between
           the Company and Chiron Corporation, as amended April 10, 1996.
*/**10.14  Sponsored Research and License Agreement, dated as of May 1, 1995, by and between
           the Company and Novo Nordisk A/S, as amended January 17, 1996 and March 17, 1996.
*/**10.15  License  Agreement, dated  as of July  17, 1995,  by and between  the Company and
           Vanderbilt University.
*/**10.16  License Agreement, dated as of May 30, 1996, by and between the Company and AMRAD
           Developments PTY Ltd.
  **10.17  Lease Agreement, dated as of November 1994, by and between the Company and Thomas
           R. Eggers.
  **10.18  Lease, Service and Affiliation  Agreement, entered into as  of February 1995,  by
           and between the Company and The Ohio State University.
  **10.19  Employment  Agreement,  dated January  3, 1993,  by and  between the  Company and
           Douglass B. Given.
   +10.20  Intercompany Services Agreement, dated  as of June   , 1996,  by and between  the
           Company and Interneuron Pharmaceuticals, Inc.
</TABLE>
    
 
                                      II-4
<PAGE>
   
<TABLE>
<C>        <S>
   +10.21  Tax  Allocation Agreement, dated as  of June  , 1996,  by and between the Company
           and Interneuron Pharmaceuticals, Inc.
     23.1  Consent of Coopers & Lybrand L.L.P.
   **23.2  Consent of Pennie & Edmonds.
   **23.3  Consent of Morrison & Foerster LLP (included in Exhibit 5.1).
   **24.1  Power of Attorney.
   **27    Financial Data Schedule.
</TABLE>
    
 
- --------------
   
+   Documents to be filed by amendment.
    
 
   
*   Documents for which confidential treatment has been requested.
    
 
   
**  Exhibit previously filed.
    
 
    (B) FINANCIAL STATEMENT SCHEDULES.
 
    None.
 
    Schedules not  listed  above  have  been  omitted  because  the  information
required  to be set forth therein is not applicable or is shown in the financial
statements or notes thereto.
 
ITEM 17.  UNDERTAKINGS.
 
    The undersigned registrant hereby undertakes to provide to the  Underwriters
at  the closing  specified in the  Underwriting Agreement,  certificates in such
denominations and registered in  such names as required  by the Underwriters  to
permit prompt delivery to each purchaser.
 
    Insofar  as indemnification for liabilities arising under the Securities Act
may  be  permitted  to  directors,  officers  and  controlling  persons  of  the
registrant  pursuant to  the provisions described  in Item  14, the Underwriting
Agreement, or otherwise, the registrant has been advised that in the opinion  of
the  Securities and Exchange  Commission such indemnification  is against public
policy as expressed in the Securities  Act and is, therefore, unenforceable.  In
the  event that a claim for indemnification against such liabilities (other than
the payment  by the  registrant of  expenses  incurred or  paid by  a  director,
officer or controlling person of the registrant in the successful defense of any
action,   suit,  or  proceeding)  is  asserted  by  such  director,  officer  or
controlling person in connection with the securities being registered hereunder,
the registrant will, unless in  the opinion of its  counsel the matter has  been
settled  by controlling precedent, submit to a court of appropriate jurisdiction
the question whether  such indemnification  by it  is against  public policy  as
expressed  in the Securities Act and will  be governed by the final adjudication
of such issue.
 
    The undersigned registrant undertakes that:
 
        (1) For purposes of determining any liability under the Securities  Act,
    the  information omitted from  the form of  prospectus filed as  part of the
    Registration Statement in reliance upon Rule 430A and contained in the  form
    of  prospectus filed by the registrant pursuant  to Rule 424(b)(1) or (4) or
    497(h) under  the  Securities  Act  shall  be  deemed  to  be  part  of  the
    Registration Statement as of the time it was declared effective.
 
        (2)  For the purpose  of determining any  liability under the Securities
    Act, each post-effective amendment that contains a form of prospectus  shall
    be  deemed to  be a  new registration  statement relating  to the securities
    offered therein, and the offering of  such securities at that time shall  be
    deemed to be in the initial bona fide offering thereof.
 
                                      II-5
<PAGE>
                                   SIGNATURES
 
   
    Pursuant  to the requirements of the  Securities Act of 1933, the Registrant
has duly caused this Amendment to the Registration Statement to be signed on its
behalf by the undersigned, thereunto duly  authorized, in the City of  Columbus,
State of Ohio, on July 11, 1996.
    
 
                                          PROGENITOR, INC.
 
   
                                          By:        /s/ DOUGLASS B. GIVEN
    
 
                                             -----------------------------------
                                               Douglass B. Given, M.D., Ph.D.
                                             PRESIDENT, CHIEF EXECUTIVE OFFICER
                                                         AND DIRECTOR
 
   
    Pursuant   to  the  requirements  of  the   Securities  Act  of  1933,  this
Registration  Statement  has  been  signed  by  the  following  persons  in  the
capacities and on the dates indicated:
    
 
   
<TABLE>
<CAPTION>
                      SIGNATURE                                          TITLE                         DATE
- ------------------------------------------------------  ----------------------------------------  ---------------
 
<C>                                                     <S>                                       <C>
                /s/ DOUGLASS B. GIVEN
     -------------------------------------------        President, Chief Executive Officer and     July 11, 1996
            Douglass B. Given, M.D., Ph.D.               Director
 
                /s/ DAVID B. BITTNER*
     -------------------------------------------        Acting Chief Financial Officer             July 11, 1996
                   David B. Bittner
 
                /s/ ROBERT P. AXLINE*
     -------------------------------------------        Director                                   July 11, 1996
                   Robert P. Axline
 
                 /s/ GLENN L. COOPER*
     -------------------------------------------        Director                                   July 11, 1996
                 Glenn L. Cooper M.D.
 
             /s/ ALEXANDER M. HAIG, JR.*
     -------------------------------------------        Director                                   July 11, 1996
                Alexander M. Haig, Jr.
 
                  /s/ MORRIS LASTER*
     -------------------------------------------        Director                                   July 11, 1996
                 Morris Laster, M.D.
 
                /s/ JERRY P. PEPPERS*
     -------------------------------------------        Director                                   July 11, 1996
                   Jerry P. Peppers
 
                /s/ DAVID B. SHARROCK*
     -------------------------------------------        Director                                   July 11, 1996
                  David B. Sharrock
 
         *By:          /S/ DOUGLASS B. GIVEN
     -------------------------------------------
            Douglass B. Given, M.D., Ph.D.
                   ATTORNEY-IN-FACT
</TABLE>
    
 
   
                                      II-6
    
<PAGE>
                                 EXHIBIT INDEX
 
   
<TABLE>
<CAPTION>
 EXHIBIT
   NO.                                                 EXHIBIT                                                PAGE
- ----------  ----------------------------------------------------------------------------------------------  ---------
<C>         <S>                                                                                             <C>
     +1.1   Form of Underwriting Agreement................................................................
      3.1   Form of Amended and Restated Certificate of Incorporation of the Company......................
      3.2   Amended and Restated Bylaws of the Company....................................................
     +4.1   Specimen Stock Certificate of the Company.....................................................
      4.2   Reference is made to Exhibits 3.1 and 3.2.....................................................
    **5.1   Opinion of Morrison & Foerster LLP............................................................
     10.1   Form of Indemnification Agreement entered into between the Company and its directors and
            executive officers............................................................................
   **10.2   The Company's 1992 Stock Option Plan..........................................................
   **10.3   Form of Incentive Stock Option Agreement under the 1992 Stock Option Plan.....................
   **10.4   Form of Non-Qualified Stock Option Agreement under the 1992 Stock Option
            Plan..........................................................................................
     10.5   The Company's 1996 Stock Incentive Plan and form of Stock Option Agreement....................
   **10.6   Form of Investors' Rights Agreement, entered into among the Company, Interneuron
            Pharmaceuticals, Inc., Transcell Technologies, Inc., and the holders of the Company's
            Preferred Stock, Series B.....................................................................
 */**10.7   License Agreement, dated as of January 28, 1992, by and between Scimark Corp., The Castle
            Group Ltd. and Ohio University, as amended October 15, 1993...................................
 */**10.8   Sponsored Research Agreement, dated January 31, 1992, by and between Scimark Corp. and Ohio
            University, as amended October 15, 1993, February 16, 1994, November 16, 1994 and November 22,
            1995..........................................................................................
 */**10.9   License Agreement, dated as of April 1, 1993, by and between the Company and Ohio
            University....................................................................................
 */**10.10  Sponsored Research Agreement, dated April 1, 1993, by and between the Company and Ohio
            University, as amended August 7, 1995 and November 22, 1995...................................
   **10.11  License Agreement, dated as of June 8, 1994, by and between the Company and Associated
            Universities, Inc.............................................................................
 */**10.12  Standard License Agreement, dated as of September 1, 1994, by and between the Company and the
            Wisconsin Alumni Research Foundation, as amended June 2, 1995.................................
 */**10.13  License and Collaboration Agreement, dated as of March 31, 1995, by and between the Company
            and Chiron Corporation, as amended April 10, 1996.............................................
 */**10.14  Sponsored Research and License Agreement, dated as of May 1, 1995, by and between the Company
            and Novo Nordisk A/S, as amended January 17, 1996 and March 17, 1996..........................
 */**10.15  License Agreement, dated as of July 17, 1995, by and between the Company and Vanderbilt
            University....................................................................................
 */**10.16  License Agreement, dated as of May 30, 1996, by and between the Company and AMRAD Developments
            PTY Ltd.......................................................................................
   **10.17  Lease Agreement, dated as of November 1994, by and between the Company and Thomas R.
            Eggers........................................................................................
   **10.18  Lease, Service and Affiliation Agreement, entered into as of February 1995, by and between the
            Company and The Ohio State University.........................................................
</TABLE>
    
<PAGE>
   
<TABLE>
<CAPTION>
 EXHIBIT
   NO.                                                 EXHIBIT                                                PAGE
- ----------  ----------------------------------------------------------------------------------------------  ---------
   **10.19  Employment Agreement, dated January 3, 1993, by and between the Company and Douglass B.
            Given.........................................................................................
<C>         <S>                                                                                             <C>
    +10.20  Intercompany Services Agreement, dated as of June  , 1996, by and between the Company and
            Interneuron Pharmaceuticals, Inc..............................................................
    +10.21  Tax Allocation Agreement, dated as of June  , 1996, by and between the Company and Interneuron
            Pharmaceuticals, Inc..........................................................................
     23.1   Consent of Coopers & Lybrand L.L.P............................................................
   **23.2   Consent of Pennie & Edmonds...................................................................
   **23.3   Consent of Morrison & Foerster LLP (included in Exhibit 5.1)..................................
   **24.1   Power of Attorney.............................................................................
   **27     Financial Data Schedule.......................................................................
</TABLE>
    
 
- --------------
   
+   Documents to be filed by amendment.
    
 
   
*   Documents for which confidential treatment has been requested.
    
 
   
**  Exhibit previously filed.
    

<PAGE>


                 AMENDED AND RESTATED CERTIFICATE OF INCORPORATION OF
                                   PROGENITOR, INC.

    Douglass B. Given and Gavin B. Grover hereby certify that:

    1.   The name of this corporation is Progenitor, Inc. and the date of
filing the original Certificate of Incorporation of this corporation with the
Secretary of State of the State of Delaware is February 25, 1992.

    2.   They are the duly elected and acting President and Secretary,
respectively, of Progenitor, Inc., a Delaware corporation.

    3.   The Certificate of Incorporation of this corporation is hereby amended
and restated to read as follows:

                                          "I

    The name of the corporation is Progenitor, Inc. (the "Corporation").

                                          II

    The address of the registered office of the Corporation in the State of
Delaware is the Corporation Trust Center, 1209 Orange Street, in the City of
Wilmington, County of New Castle, and the name of its registered agent at that
address is The Corporation Trust Company.

                                         III

    The purpose of the Corporation is to engage in any lawful act or activity
for which a corporation may be organized under the General Corporation Law of
the State of Delaware.

                                          IV

    The total number of shares of all classes of stock that the Corporation is
authorized to issue is Forty-Seven Million (47,000,000) shares, consisting of
Thirty-Nine Million (39,000,000) shares of Common Stock with a par value of
$.001 per share, Two Million One Hundred Twenty Thousand (2,120,000) shares of
Preferred Stock, Series A, with a par value of $.01 per share, Eight Hundred
Eighty Thousand (880,000) shares of Preferred Stock, Series B, with a par value
of $.01 per share, and Five Million (5,000,000) shares of additional Preferred
Stock ("Additional Preferred Stock") with a par value of $.001 per share.  The
rights, preferences, privileges and restrictions granted to and imposed upon
such classes of shares are set forth below in this Article.

    A..  COMMON STOCK.

         1.   DIVIDEND RIGHTS.  Subject to the prior rights of holders of all
classes of stock at the time outstanding having prior rights as to dividends,
the holders of the Common Stock shall be


                                          1

<PAGE>

entitled to receive, when and as declared by the Board of Directors, out of any
assets of the Corporation legally available therefor, such dividends as may be
declared from time to time by the Board of Directors.

         2.   LIQUIDATION RIGHTS.  Upon the liquidation, dissolution or winding
up of the Corporation, the assets of the Corporation shall be distributed
ratably among holders of Common Stock in proportion to the amount of such stock
owned by each such holder, subject to any liquidation rights of any then
outstanding Preferred Stock.

         3.   REDEMPTION.  The Common Stock is not redeemable.

         4.   VOTING RIGHTS.  The holder of each share of Common Stock shall
have the right to one vote, shall be entitled to notice of any shareholders'
meeting in accordance with the Bylaws of this Corporation, except as otherwise
provided herein, and shall be entitled to vote upon such matters and in such
manner as may be provided by law.

    B.   PREFERRED STOCK.

         1.   SERIES A AND SERIES B PREFERRED STOCK.  The rights, preferences,
privileges and restrictions granted to and imposed upon the Series A and Series
B Preferred Stock shall be as set forth in the Certificates of Designation for
such series of Preferred Stock filed with the Secretary of State on January 4,
1995 and December 29, 1994, respectively; PROVIDED, HOWEVER, that upon the
conversion of the shares of such series of Preferred Stock into shares of Common
Stock in accordance with the terms of their respective Certificates of
Designation, no share or shares of Series A or Series B Preferred Stock shall be
reissued, and all such shares shall be canceled, retired and eliminated from the
shares that the Corporation shall be authorized to issue.

         2.   ADDITIONAL PREFERRED STOCK.  The Additional Preferred Stock
authorized by this Certificate of Incorporation may be issued from time to time
in series.  The Board of Directors is hereby authorized to fix or alter the
rights, preferences, privileges, and restrictions granted to or imposed upon any
series of Additional Preferred Stock (including the dividend rights, conversion
rights, voting rights, terms of redemption, liquidation preferences and sinking
fund terms thereof), and the number of shares constituting any such series and
the designation thereof.  Subject to compliance with applicable protective
voting rights which have been or may be granted to the Series A and Series B
Preferred Stock, or Additional Preferred Stock or series thereof (collectively,
"Preferred Stock") in Certificates of Designation or the Corporation's
Certificate of Incorporation ("Protective Provisions"), but notwithstanding any
other rights of the Preferred Stock or any series thereof, the rights,
privileges, preferences, and restrictions of any such additional series may be
subordinated to, PARI PASSU with (including, without limitation, inclusion in
provisions with respect to liquidation and acquisition preferences, redemption,
and/or approval of matters by vote or written consent) or senior to any of those
of any present or future class or series of Preferred Stock or Common Stock.
Subject to the compliance with applicable Protective Provisions, the Board of
Directors is also authorized to increase or decrease the number of shares of any
series prior or subsequent to the issue of that series, but not below the number
of shares of such series then outstanding.  In case the number of shares of any
series shall be so decreased, the shares constituting such decrease shall resume
the status which they had prior to the adoption of the resolution originally
fixing the number of shares of such series.

    Upon amendment and restatement of the Certificate of Incorporation as set
forth herein, each authorized share of Common Stock of the Corporation issued
and outstanding prior to such amendment


                                          2

<PAGE>

and restatement shall be automatically reclassified, without any action by the
holder thereof, into one-half (1/2) of one share of fully-paid and nonassessable
Common Stock. No fractional shares of Common Stock shall be issued upon such
reclassification.  Instead of any fractional share of Common Stock that would
otherwise be issuable upon such reclassification, the Corporation shall pay cash
to the holder thereof equal to the product of such fraction multiplied by the
fair market value of one share of Common Stock after such reclassification, as
determined by the Board of Directors of the Corporation in good faith exercising
reasonable business judgment.

                                          V

    A.   To the fullest extent permitted by Delaware statutory or decisional
law, as amended or interpreted, no director of the Corporation shall be
personally liable to the Corporation or its stockholders for monetary damages
for breach of fiduciary duty as a director.  This Article V does not affect the
availability of equitable remedies for breach of fiduciary duties.

    B.   Any repeal or modification of this Article V shall be prospective and
shall not affect the rights under this Article V in effect at the time of the
alleged occurrence of any act or omission to act giving rise to liability or
indemnification.

                                          VI

    The Corporation shall, to the fullest extent permitted by Section 145 of
the General Corporation Law of the State of Delaware, as amended from time to
time, indemnify all persons whom it may indemnify pursuant thereto.

                                         VII

    For the management of the business and for the conduct of the affairs of
the Corporation, and in further definition, limitation and regulation of the
powers of the Corporation, of its directors and of its stockholders or any class
thereof, as the case may be, it is further provided that:

    A.   The management of the business and the conduct of the affairs of the
Corporation shall be vested in its Board of Directors.  The number of directors
which shall constitute the whole Board of Directors shall be fixed by the Board
of Directors in the manner provided in the Bylaws.

    A.   The Board of Directors may from time to time make, amend, supplement
or repeal the Bylaws.

    C.   The directors of the Corporation need not be elected by written ballot
unless the Bylaws so provide.

                                       VIII

    Whenever a compromise or arrangement is proposed between this Corporation
and its creditors or any class of them and/or between this Corporation and its
stockholders or any class of them, any court of equitable jurisdiction within
the State of Delaware may, on the application in a summary way of this
Corporation or of any creditor or stockholder thereof, or on the


                                          3

<PAGE>

application of any receiver or receivers appointed for this Corporation under
the provisions of Section 291 of Title 8 of the Delaware Code or on the
application of trustees in dissolution or of any receiver or receivers appointed
for this Corporation under the provisions of Section 279 of Title 8 of the
Delaware Code order a meeting of the creditors or class of creditors, and/or of
the stockholders or class of stockholders of this Corporation, as the case may
be, to be summoned in such manner as the said court directs.  If a majority in
number representing three-fourths in value of the creditors or class of
creditors, and/or of the stockholders or class of stockholders of this
Corporation, as the case may be, agree to any compromise or arrangement and to
any reorganization of this Corporation as a consequence of such compromise or
arrangement, the said compromise or arrangement and the said reorganization
shall, if sanctioned by the court to which the said application has been made,
be binding on all the creditors or class of creditors, and/or on all the
stockholders or class of stockholders, of this Corporation, as the case may be,
and also on this Corporation.

                                          IX

    The Corporation reserves the right to amend, alter, change or repeal any
provision contained in this Certificate of Incorporation, in the manner now or
hereafter prescribed by statute, and all rights conferred upon the stockholders
herein are granted subject to this right."

                                         ****

    1.   This Amended and Restated Certificate of Incorporation has been duly
approved and adopted by the Stockholders of this Corporation in accordance with
the provisions of Sections 228, 242 and 245 of the General Corporation Law of
the State of Delaware.

    IN WITNESS WHEREOF, Progenitor, Inc. has caused this Amended and Restated
Certificate of Incorporation to be signed by the President and the Secretary on
this ______ day of July 1996.

                                  PROGENITOR, INC.

                                   By:
                                      -----------------------------------------
                                             Douglass B. Given, President

ATTEST:

By:
    -------------------------------
    Gavin B. Grover, Secretary


                                          4


<PAGE>

                                 AMENDED AND RESTATED

                                        BYLAWS

                                          OF

                                   PROGENITOR, INC.

                                      ARTICLE I

                                       OFFICES

    SECTION 1. REGISTERED OFFICE.  The registered office of Progenitor, Inc.
(the "Corporation") in the State of Delaware shall be in the City of Wilmington,
County of New Castle.

    SECTION 2. PRINCIPAL OFFICE.  The principal office for the transaction of
business of the Corporation shall be at such location, within or without the
State of Delaware, as shall be designated by the Board of Directors.

    SECTION 3. OTHER OFFICES.  The Corporation shall also have offices at such
other places, both within and without the State of Delaware as the Board of
Directors may from time to time determine or the business of the Corporation may
require.

                                      ARTICLE II

                                STOCKHOLDERS' MEETINGS

    SECTION 1. PLACE OF MEETINGS.  Meetings of the stockholders of the
Corporation shall be held at such place, either within or without the State of
Delaware, as may be designated from time to time by the Board of Directors, or,
if not so designated, then at the office of the Corporation required to be
maintained pursuant to Section 2 of Article I hereof.

    SECTION 2. ANNUAL MEETINGS.  The annual meetings of the stockholders of the
Corporation, commencing with the year 1996, for the purpose of election of
directors and for such other business as may lawfully come before it, shall be
held on such date and at such time as may be designated from time to time by the
Board of Directors.

    SECTION 3. SPECIAL MEETINGS.  Special Meetings of the stockholders of the
Corporation may be called, for any purpose or purposes, by the Chairman of the
Board or the President or the Board of Directors at any time.  Upon written
request of any stockholder or stockholders holding in the aggregate ten percent
(10%) of the voting power of all stockholders delivered in person or sent by
registered mail to the Chairman of the Board, President or Secretary of the
Corporation, the Secretary shall call a special meeting of stockholders to be
held at the office of the Corporation


                                          1

<PAGE>

required to be maintained pursuant to Section 2 of Article I hereof at such time
as the Secretary may fix, such meeting to be held not less than ten nor more
than sixty days after the receipt of such request, and if the Secretary shall
neglect or refuse to call such meeting, within seven days after the receipt of
such request, the stockholder making such request may do so.

    SECTION 4. NOTICE OF MEETINGS.

    (a)  Except as otherwise provided by law or the Certificate of
Incorporation, written notice of each meeting of stockholders, specifying the
place, date and hour and purpose or purposes of the meeting, shall be given not
less than ten nor more than sixty days before the date of the meeting to each
stockholder entitled to vote thereat, directed to his address as it appears upon
the books of the Corporation; except that where the matter to be acted on is a
merger or consolidation of the Corporation or a sale, lease or exchange of all
or substantially all of its assets, such notice shall be given not less than
twenty (20) nor more than sixty (60) days prior to such meeting.

    (b)  If at any meeting action is proposed to be taken which, if taken,
would entitle shareholders fulfilling the requirements of section 262(d) of the
Delaware General Corporation Law to an appraisal of the fair value of their
shares, the notice of such meeting shall contain a statement of that purpose and
to that effect and shall be accompanied by a copy of that statutory section.

    (c)  When a meeting is adjourned to another time or place, notice need not
be given of the adjourned meeting if the time and place thereof are announced at
the meeting at which the adjournment is taken unless the adjournment is for more
than thirty days, or unless after the adjournment a new record date is fixed for
the adjourned meeting, in which event a notice of the adjourned meeting shall be
given to each stockholder of record entitled to vote at the meeting.

    (d)  Notice of the time, place and purpose of any meeting of stockholders
may be waived in writing, either before or after such meeting, and to the extent
permitted by law, will be waived by any stockholder by his attendance thereat,
in person or by proxy.  Any stockholder so waiving notice of such meeting shall
be bound by the proceedings of any such meeting in all respects as if due notice
thereof had been given.

    (e)  Unless and until voted, every proxy shall be revocable at the pleasure
of the person who executed it or of his legal representatives or assigns, except
in those cases where an irrevocable proxy permitted by statute has been given.

    SECTION 5. QUORUM AND VOTING.

    (a)  At all meetings of stockholders, except where otherwise provided by
law, the Certificate of Incorporation, or these Amended and Restated Bylaws
(hereinafter, "Bylaws"), the presence, in person or by proxy duly authorized, of
the holders of a majority of the outstanding shares of stock entitled to vote
shall constitute a quorum for the transaction of business. Shares, the voting of
which at said meeting have been enjoined, or which for any reason cannot be
lawfully voted at such meeting, shall not be counted to determine a quorum at
said meeting.  In the absence of a quorum, any meeting of stockholders may be
adjourned, from time to time, by vote of the holders of a majority of the shares
represented thereat, but no other business shall be transacted at


                                          2

<PAGE>

such meeting.  At such adjourned meeting at which a quorum is present or
represented any business may be transacted which might have been transacted at
the original meeting.  The stockholders present at a duly called or convened
meeting, at which a quorum is present, may continue to transact business until
adjournment, notwithstanding the withdrawal of enough stockholders to leave less
than a quorum.

    (b)  Except as otherwise provided by law, the Certificate of Incorporation
or these Bylaws, all action taken by the holders of a majority of the voting
power represented at any meeting at which a quorum is present shall be valid and
binding upon the Corporation.

    (c)  Where a separate vote by a class or classes is required, a majority of
the outstanding shares of such class or classes, present in person or
represented by proxy, shall constitute a quorum entitled to take action with
respect to that vote on that matter and the affirmative vote of the majority of
shares of such class or classes present in person or represented by proxy at the
meeting shall be the act of such class.

    SECTION 6. FIXING RECORD DATES.

    (a)  In order that the Corporation may determine the stockholders entitled
to notice of or to vote at any meeting of stockholders or any adjournment
thereof, the Board of Directors may fix a record date, which record date shall
not precede the date upon which the resolution fixing the record date is adopted
by the Board of Directors, and which record date shall not be more than sixty
nor less than ten days before the date of such meeting.  If no record date is
fixed by the Board of Directors, the record date for determining stockholders
entitled to notice of or to vote at a meeting of stockholders shall be at the
close of business on the day next preceding the day on which notice is given,
or, if notice is waived, at the close of business on the day next preceding the
date on which the meeting is held.  A determination of stockholders of record
entitled to notice of or to vote at a meeting of stockholders shall apply to any
adjournment of the meeting; provided, however, that the Board of Directors may
fix a new record date for the adjourned meeting.

    (b)  In order that the Corporation may determine the stockholders entitled
to consent to corporate action in writing without a meeting, the Board of
Directors may fix a record date, which record date shall not precede the date
upon which the resolution fixing the record date is adopted by the Board of
Directors, and which date shall not be more than ten days after the date upon
which the resolution fixing the record date is adopted by the Board of
Directors.  If no record date has been fixed by the Board of Directors, the
record date for determining stockholders entitled to consent to corporate action
in writing without a meeting, when no prior action by the Board of Directors is
required by the Delaware General Corporation Law, shall be the first date on
which a signed written consent setting forth the action taken or proposed to be
taken is delivered to the Corporation by delivery to its registered office in
Delaware, its principal place of business, or an officer or agent of the
Corporation having custody of the book in which proceedings of meetings of
stockholders are recorded.  Delivery made to the Corporation's registered office
shall be by hand or by certified or registered mail, return receipt requested.
If no record date has been fixed by the Board of Directors and prior action by
the Board of Directors is required by law, the record date for determining
stockholders entitled to consent to corporate action in writing without a
meeting shall


                                          3

<PAGE>

be at the close of business on the day on which the Board of Directors adopts
the resolution taking such prior action.

    (c)  In order that the Corporation may determine the stockholders entitled
to receive payment of any dividend or other distribution or allotment of any
rights or the stockholders entitled to exercise any rights in respect of any
change, conversion or exchange of stock, or for the purpose of any other lawful
action, the Board of Directors may fix a record date, which record date shall
not precede the date upon which the resolution fixing the record date is
adopted, and which record date shall be not more than sixty days prior to such
action.  If no record date is fixed, the record date for determining
stockholders for any such purpose shall be at the close of business on the day
on which the Board of Directors adopts the resolution relating thereto.

    SECTION 7. VOTING RIGHTS.

   
    (a)  Except as otherwise provided by law, only persons in whose names
shares entitled to vote stand on the stock records of the Corporation on the
record date for determining the stockholders entitled to vote at said meeting
shall be entitled to vote at such meeting.  Shares standing in the names of two
or more persons shall be voted or represented in accordance with the
determination of the majority of such persons, or, if only one of such persons
is present in person or represented by proxy, such person shall have the right
to vote such shares and such shares shall be deemed to be represented for the
purpose of determining a quorum.
    

   
    (b)  Every person entitled to vote or execute consents shall have the right
to do so either in person or by an agent or agents authorized by a written proxy
executed by such person or his duly authorized agent, which proxy shall be filed
with the Secretary of the Corporation at or before the meeting at which it is to
be used.  Said proxy so appointed need not be a stockholder.  No proxy shall be
voted on after three years from its date unless the proxy provides for a longer
period.
    

   
    (c)  Without limiting the manner in which a stockholder may authorize
another person or persons to act for him as proxy pursuant to subsection (b) of
this Section 7, the following shall constitute a valid means by which a
stockholder may grant such authority:
    

         (1)  A stockholder may execute a writing authorizing another person or
persons to act for him as proxy.  Execution may be accomplished by the
stockholder or his authorized officer, director, employee or agent signing such
writing or causing his or her signature to be affixed to such writing by any
reasonable means including, but not limited to, by facsimile signature.

         (2)  A stockholder may authorize another person or persons to act for
him as proxy by transmitting or authorizing the transmission of a telegram,
cablegram, or other means of electronic transmission to the person who will be
the holder of the proxy or to a proxy solicitation firm, proxy support service
organization or like agent duly authorized by the person who will be the holder
of the proxy to receive such transmission, provided that any such telegram,
cablegram or other means of electronic transmission must either set forth or be
submitted with information from which it can be determined that the telegram,
cablegram or other electronic transmission was authorized by the stockholder.
Such authorization can be established by the signature of the


                                          4

<PAGE>

stockholder on the proxy, either in writing or by a signature stamp or facsimile
signature, or by a number or symbol from which the identity of the stockholder
can be determined, or by any other procedure deemed appropriate by the
inspectors or other persons making the determination as to due authorization.
If it is determined that such telegrams, cablegrams or other electronic
transmissions are valid, the inspectors or, if there are no inspectors, such
other persons making that determination shall specify the information upon which
they relied.

    (d)  Any copy, facsimile telecommunication or other reliable reproduction
of the writing or transmission created pursuant to subsection (c) of this
Section 7 may be substituted or used in lieu of the original writing or
transmission for any and all purposes for which the original writing or
transmission could be used, provided that such copy, facsimile telecommunication
or other reproduction shall be a complete reproduction of the entire original
writing or transmission.

    SECTION 8. LIST OF STOCKHOLDERS.  The officer who has charge of the stock
ledger of the Corporation shall prepare and make, at least ten days before every
meeting of stockholders, a complete list of the stockholders entitled to vote at
said meeting, arranged in alphabetical order, showing the address of and the
number of shares registered in the name of each stockholder.  Such list shall be
open to the examination of any stockholder, for any purpose germane to the
meeting, during ordinary business hours, for a period of at least ten days prior
to the meeting, either at a place within the city where the meeting is to be
held and which place shall be specified in the notice of the meeting, or, if not
specified, at the place where said meeting is to be held, and the list shall be
produced and kept at the time and place of meeting during the whole time
thereof, and may be inspected by any stockholder who is present.

    SECTION 9. ACTION WITHOUT MEETING.  Unless otherwise provided in the
Certificate of Incorporation, any action required by statute to be taken at any
annual or special meeting of stockholders of the Corporation, or any action
which may be taken at any annual or special meeting of such stockholders, may be
taken without a meeting, without prior notice and without a vote, if a consent
or consents in writing, setting forth the action so taken, are signed by the
holders of outstanding stock having not less than the minimum number of votes
that would be necessary to authorize or take such action at a meeting at which
all shares entitled to vote thereon were present and voted.  To be effective, a
written consent must be delivered to the Corporation by delivery to its
registered office in Delaware, its principal place of business, or an officer or
agent of the Corporation having custody of the book in which proceedings of
meetings of stockholders are recorded.  Delivery made to the Corporation's
registered office shall be by hand or by certified or registered mail, return
receipt requested.  Every written consent shall bear the date of signature of
each stockholder who signs the consent and no written consent shall be effective
to take the corporate action referred to therein unless, within sixty days of
the earliest dated consent delivered in the manner required by this Section to
the Corporation, written consents signed by a sufficient number of holders to
take action are delivered to the Corporation in accordance with this Section.
Prompt notice of the taking of the corporate action without a meeting by less
than unanimous written consent shall be given to those stockholders who have not
consented in writing.


                                          5

<PAGE>

    SECTION 10. VOTING PROCEDURES AND INSPECTORS OF ELECTIONS.

    (a)  The Corporation shall, in advance of any meeting of stockholders,
appoint one or more inspectors to act at the meeting and make a written report
thereof.  The Corporation may designate one or more persons as alternate
inspectors to replace any inspector who fails to act.  If no inspector or
alternate is able to act at a meeting of stockholders, the person presiding at
the meeting shall appoint one or more inspectors to act at the meeting.  Each
inspector, before entering upon the discharge of his duties, shall take and sign
an oath faithfully to execute the duties of inspector with strict impartiality
and according to the best of his ability.

    (b)  The inspectors shall (i) ascertain the number of shares outstanding
and the voting power of each, (ii) determine the shares represented at a meeting
and the validity of proxies and ballots, (iii) count all votes and ballots, (iv)
determine and retain for a reasonable period a record of the disposition of any
challenges made to any determination by the inspectors, and (v) certify their
determination of the number of shares represented at the meeting, and their
count of all votes and ballots.  The inspectors may appoint or retain other
persons or entities to assist the inspectors in the performance of the duties of
the inspectors.

    (c)  The date and time of the opening and the closing of the polls for each
matter upon which the stockholders will vote at a meeting shall be announced at
the meeting.  No ballot, proxies or votes, nor any revocations thereof or
changes thereto, shall be accepted by the inspectors after the closing of the
polls unless the Court of Chancery upon application by a stockholder shall
determine otherwise.

    (d)  In determining the validity and counting of proxies and ballots, the
inspectors shall be limited to an examination of the proxies, any envelopes
submitted with those proxies, any information provided in accordance with
Section 212(c)(2) of the Delaware General Corporation Law, ballots and the
regular books and records of the Corporation, except that the inspectors may
consider other reliable information for the limited purpose of reconciling
proxies and ballots submitted by or on behalf of banks, brokers, their nominees
or similar persons which represent more votes than the holder of a proxy is
authorized by the record owner to cast or more votes than the stockholder holds
of record.  If the inspectors consider other reliable information for the
limited purpose permitted herein, the inspectors at the time they make their
certification pursuant to subsection (b)(v) of this Section 10 shall specify the
precise information considered by them including the person or persons from whom
they obtained the information, when the information was obtained, the means by
which the information was obtained and the basis for the inspectors' belief that
such information is accurate and reliable.

                                     ARTICLE III

                                      DIRECTORS

    SECTION 1. POWERS.  Subject to the provisions of the Delaware Corporation
Law and any limitations in the Certificate of Incorporation relating to action
required to be approved by the shareholders or by the outstanding shares, the
business and affairs of the Corporation shall be


                                          6

<PAGE>

managed and all corporate powers shall be exercised by or under the direction of
the Board of Directors.  The Board of Directors may delegate the management of
the day-to-day operation of the business of the Corporation to a management
company or other person provided that the business and affairs of the
Corporation shall be managed and all corporate powers shall be exercised under
the ultimate direction of the Board of Directors.

    SECTION 2. APPROVAL OF LOANS TO OFFICERS.  The Corporation may, upon
approval of the Board of Directors alone, make loans of money or property to, or
guarantee the obligations of, any officer (whether or not a director) of the
Corporation or of its parent, or adopt an employee benefit plan authorizing such
loans or guaranties provided that:

         (a)  the Board of Directors determines that such a loan, guaranty, or
plan may reasonably be expected to benefit the Corporation;

         (b)  the approval by the Board of Directors is by a vote sufficient
without counting the vote of any interested director(s); and

         (c)  the loan is otherwise made in compliance with Section 143 of the
Delaware General Corporation Law.

    SECTION 3. NUMBER AND TERM OF OFFICE.  The Board of Directors shall consist
of one or more members, the number of which shall be seven (7) until changed
thereafter from time to time by resolution of the Board.  Directors need not be
stockholders of the Corporation.  Each director shall hold office until a
successor is elected and qualified or until the director resigns or is removed.

    SECTION 4. VACANCIES.  Vacancies and newly created directorships resulting
from any increase in the authorized number of directors may be filled by a
majority of the directors then in office, although less than a quorum, or by a
sole remaining director, and each director so elected shall hold office for the
unexpired portion of the term of the director whose place shall be vacant, and
until his successor shall have been duly elected and qualified.  A vacancy in
the Board of Directors shall be deemed to exist under this Section 4 in the case
of the death, removal or resignation of any director, or if the stockholders
fail at any meeting of stockholders at which directors are to be elected
(including any meeting referred to in Section 6 below) to elect the number of
directors then constituting the whole Board.

    SECTION 5. RESIGNATIONS AND REMOVALS.

         (a)  Any director may resign at any time by delivering his written
resignation to the Secretary, such resignation to specify whether it will be
effective at a particular time, upon receipt by the Secretary or at the pleasure
of the Board of Directors.  If no such specification is made it shall be deemed
effective at the pleasure of the Board of Directors.  When one or more directors
shall resign from the Board, effective at a future date, a majority of the
directors then in office, including those who have so resigned, shall have power
to fill such vacancy or vacancies, the vote thereon to take effect when such
resignation or resignations shall become effective, and each director so chosen
shall hold office for the unexpired portion of the term of the director whose
place shall be vacated and until his successor shall have been duly elected and
qualified.


                                          7

<PAGE>

         (b)  At a special meeting of stockholders called for the purpose in
the manner hereinabove provided, the Board of Directors, or any individual
director, may be removed from office, with or without cause, and a new director
or directors elected by a vote of stockholders holding a majority of the
outstanding shares entitled to vote at an election of directors.

    SECTION 6. MEETINGS.

         (a)  The annual meeting of the Board of Directors shall be held
immediately after the annual stockholders' meeting and at the place where such
meeting is held or at the place announced by the Chairman at such meeting.  No
notice of an annual meeting of the Board of Directors shall be necessary and
such meeting shall be held for the purpose of electing officers and transacting
such other business as may lawfully come before it.

         (b)  Except as hereinafter otherwise provided, regular meetings of the
Board of Directors shall be held in the office of the Corporation required to be
maintained pursuant to Section 2 of Article I hereof.  Regular meetings of the
Board of Directors may also be held at any place within or without the State of
Delaware which has been designated by resolutions of the Board of Directors or
the written consent of all directors.

         (c)  Special meetings of the Board of Directors may be held at any
time and place within or without the State of Delaware whenever called by the
Chairman of the Board or, if there is no Chairman of the Board, by the
President, any Vice-President, the Secretary, or any two directors.

         (d)  Written notice of the time and place of all regular and special
meetings of the Board of Directors shall be delivered personally to each
director or sent by telegram or facsimile transmission at least 48 hours before
the start of the meeting, or sent by first class mail at least 120 hours before
the start of the meeting.  Notice of any meeting may be waived in writing at any
time before or after the meeting and will be waived by any director by
attendance thereat.

    SECTION 7. QUORUM AND VOTING.

         (a)  A quorum of the Board of Directors shall consist of a majority of
the exact number of directors fixed from time to time in accordance with
Section 2 of this Article of these Bylaws, but not less than one; provided,
however, at any meeting whether a quorum be present or otherwise, a majority of
the directors present may adjourn from time to time until the time fixed for the
next regular meeting of the Board of Directors, without notice other than by
announcement at the meeting.

         (b)  At each meeting of the Board at which a quorum is present all
questions and business shall be determined by a vote of a majority of the
directors present, unless a different vote be required by law, the Certificate
of Incorporation, or these Bylaws.

         (c)  Any member of the Board of Directors, or of any committee
thereof, may participate in a meeting by means of conference telephone or
similar communication equipment by means of which all persons participating in
the meeting can hear each other, and participation in a meeting by such means
shall constitute presence in person at such meeting.


                                          8

<PAGE>

         (d)  The transactions of any meeting of the Board of Directors, or any
committee thereof, however called or noticed, or wherever held, shall be as
valid as though had at a meeting duly held after regular call and notice, if a
quorum be present and if, either before or after the meeting, each of the
directors not present shall sign a written waiver of notice, or a consent to
holding such meeting, or an approval of the minutes thereof.  All such waivers,
consents or approvals shall be filed with the corporate records or made a part
of the minutes of the meeting.

    SECTION 8. ACTION WITHOUT MEETING.  Unless otherwise restricted by the
Certificate of Incorporation or these Bylaws, any action required or permitted
to be taken at any meeting of the Board of Directors or of any committee thereof
may be taken without a meeting, if all members of the Board or of such
committee, as the case may be, consent thereto in writing, and such writing or
writings are filed with the minutes of proceedings of the Board or committee.

    SECTION 9. FEES AND COMPENSATION.  Directors and members of committees may
receive such compensation, if any, for their services, and such reimbursement
for expenses, as may be fixed or determined by resolution of the Board of
Directors.

    SECTION 10. COMMITTEES.

         (a)  EXECUTIVE COMMITTEE:  The Board of Directors may, by resolution
passed by a majority of the whole Board, appoint an Executive Committee of not
less than one member, each of whom shall be a director.  The Executive
Committee, to the extent permitted by law, shall have and may exercise when the
Board of Directors is not in session all powers of the Board in the management
of the business and affairs of the Corporation, including, without limitation,
the power and authority to declare a dividend or to authorize the issuance of
stock, except such committee shall not have the power or authority to amend the
Certificate of Incorporation, to adopt an agreement of merger or consolidation,
to recommend to the stockholders the sale, lease or exchange of all or
substantially all of the Corporation's property and assets, to recommend to the
stockholders of the Corporation a dissolution of the Corporation or a revocation
of a dissolution, or to amend these Bylaws.

         (b)  OTHER COMMITTEES:  The Board of Directors may, by resolution
passed by a majority of the whole Board, from time to time appoint such other
committees as may be permitted by law.  Such other committees appointed by the
Board of Directors shall have such powers and perform such duties as may be
prescribed by the resolution or resolutions creating such committee, but in no
event shall any such committee have the powers denied to the Executive Committee
in these Bylaws.

         (c)  TERM:  The members of all committees of the Board of Directors
shall serve a term coexistent with that of the Board of Directors which shall
have appointed such committee.  The Board, subject to the provisions of
subsections (a) or (b) of this Section 10, may at any time increase or decrease
the number of members of a committee or terminate the existence of a committee;
provided, that no committee shall consist of less than one member.  The
membership of a committee member shall terminate on the date of his death or
voluntary resignation, but the Board may at any time for any reason remove any
individual committee member and the Board may fill any committee vacancy created
by death, resignation, removal or increase in the number of


                                          9

<PAGE>

members of the committee.  The Board of Directors may designate one or more
directors as alternate members of any committee, who may replace any absent or
disqualified member at any meeting of the committee, and, in addition, in the
absence or disqualification of any member of a committee, the member or members
thereof present at any meeting and not disqualified from voting, whether or not
he or they constitute a quorum, may unanimously appoint another member of the
Board of Directors to act at the meeting in the place of any such absent or
disqualified member.

         (d)  MEETINGS:  Unless the Board of Directors shall otherwise provide,
regular meetings of the Executive Committee or any other committee appointed
pursuant to this Section 10 shall be held at such times and places as are
determined by the Board of Directors, or by any such committee, and when notice
thereof has been given to each member of such committee, no further notice of
such regular meetings need be given thereafter; special meetings of any such
committee may be held at the principal office of the Corporation required to be
maintained pursuant to Section 2 of Article I hereof; or at any place which has
been designated from time to time by resolution of such committee or by written
consent of all members thereof, and may be called by any director who is a
member of such committee, upon written notice to the members of such committee
of the time and place of such special meeting given in the manner provided for
the giving of written notice to members of the Board of Directors of the time
and place of special meetings of the Board of Directors.  Notice of any special
meeting of any committee may be waived in writing at any time after the meeting
and will be waived by any director by attendance thereat.  A majority of the
authorized number of members of any such committee shall constitute a quorum for
the transaction of business, and the act of a majority of those present at any
meeting at which a quorum is present shall be the act of such committee.

                                      ARTICLE IV

                                       OFFICERS

    SECTION 1. OFFICERS DESIGNATED.  The officers of the Corporation shall
consist of the President, the Secretary and the Treasurer, and each of them
shall be appointed by the Board of Directors.  The Corporation may also have a
Chairman of the Board, one or more Vice-Presidents, a Controller, one or more
Assistant Secretaries and Assistant Treasurers, and such other officers with
such titles as may be deemed appropriate by the Board of Directors, or with
authorization from the Board of Directors by the Chairman of the Board of
Directors or the President, each of whom shall have such authority and perform
such duties are provided in these Bylaws or as the Board of Directors may from
time to time determine.   Any one person may hold any number of offices of the
Corporation at any one time unless specifically prohibited therefrom by law.
The order of the seniority of the Vice-Presidents shall be in the order of their
nomination, unless otherwise determined by the Board of Directors.   The Board
of Directors shall designate one officer as the chief financial officer of the
Corporation.  In the absence of such designation, the Treasurer shall be the
chief financial officer.  The salaries and other compensation of the officers of
the Corporation shall be fixed by or in the manner designated by the Board of
Directors.


                                          10

<PAGE>

    SECTION 2. TENURE AND DUTIES OF OFFICERS.

         (a)  GENERAL:  All officers shall hold office at the pleasure of the
Board of Directors and until their successors shall have been duly elected and
qualified, unless sooner removed.  Any officer elected or appointed by the Board
of Directors may be removed at any time by the Board of Directors.  If the
office of any officer becomes vacant for any reason, the vacancy may be filled
by the Board of Directors.  Nothing in these Bylaws shall be construed as
creating any kind of contractual right to employment with the Corporation.

         (b)  DUTIES OF THE CHAIRMAN OF THE BOARD OF DIRECTORS:  The Chairman
of the Board (if there be such an officer appointed) shall, when present,
preside at all meetings of the Board of Directors and shall perform all the
duties commonly incident to that office.  The Chairman of the Board of Directors
shall have authority to execute in the name of the Corporation bonds, contracts,
deeds, leases and other written instruments to be executed by the Corporation
(except where by law the signature of the President is required), and shall
perform such other duties and have such other powers as the Board of Directors
may from time to time determine.

         (c)  DUTIES OF PRESIDENT:  Subject to such supervisory powers, if any,
as may be given by the Board of Directors to the Chairman of the Board, the
President shall be the chief executive officer of the Corporation and shall
perform all the duties commonly incident to that office.  The President shall
have authority to execute in the name of the Corporation bonds, contracts,
deeds, leases and other written instruments to be executed by the Corporation.
The President shall preside at all meetings of the shareholders and, in the
absence of the Chairman of the Board or if there is none, at all meetings of the
Board of Directors, and shall perform such other duties as the Board of
Directors may from time to time determine.

         (d)  DUTIES OF VICE-PRESIDENTS:  The Vice-Presidents (if there be such
officers appointed), in the order of their seniority (unless otherwise
established by the Board of Directors), may assume and perform the duties of the
President in the absence or disability of the President or whenever the offices
of the Chairman of the Board and President are vacant.  The Vice-Presidents
shall have such titles, perform such other duties, and have such other powers as
the Board of Directors, the President or these Bylaws may designate from time to
time.

         (e)  DUTIES OF SECRETARY:  The Secretary shall attend all meetings of
the shareholders and of the Board of Directors and any committee thereof, and
shall record all acts and proceedings thereof in the minute book of the
Corporation.  The Secretary shall give notice, in conformity with these Bylaws,
of all meetings of the shareholders, and of all meetings of the Board of
Directors and any Committee thereof requiring notice.  The Secretary shall
perform such other duties and have such other powers as the Board of Directors
shall designate from time to time.  The President may direct any Assistant
Secretary to assume and perform the duties of the Secretary in the absence or
disability of the Secretary, and each Assistant Secretary shall perform such
other duties and have such other powers as the Board of Directors or the
President shall designate from time to time.

         (f)  DUTIES OF TREASURER:  The Treasurer shall keep or cause to be
kept the books of account of the Corporation in a thorough and proper manner,
and shall render statements of the financial affairs of the Corporation in such
form and as often as required by the Board of Directors


                                          11

<PAGE>

or the President.  The Treasurer, subject to the order of the Board of
Directors, shall have the custody of all funds and securities of the
Corporation.

    The Treasurer shall keep and maintain, or cause to be kept and maintained,
adequate and correct accounts of the properties and business transactions of the
Corporation.  The books of account shall at all reasonable times be open to
inspection by any director.

    The Treasurer shall deposit all moneys and other valuables in the name and
to the credit of the Corporation with such depositaries as may be designated by
the Board of Directors.  The Treasurer shall disburse the funds of the
Corporation as may be ordered by the Board of Directors, shall render to the
President and directors, whenever they request it, an account of all of the
Treasurer's transactions as Treasurer and of the financial condition of the
Corporation, and shall have such other powers and perform such other duties as
may be prescribed by the Board of Directors or these Bylaws.

    The Treasurer shall perform all other duties commonly incident to his
office and shall perform such other duties and have such other powers as the
Board of Directors or the President shall designate from time to time.  The
President may direct any Assistant Treasurer to assume and perform the duties of
the Treasurer in the absence or disability of the Treasurer, and each Assistant
Treasurer shall perform such other duties and have such other powers as the
Board of Directors or the President shall designate from time to time.

         (g)  DUTIES OF CONTROLLER:  The Controller (if there be such an
officer appointed) shall be responsible for the establishment and maintenance of
accounting and other systems required to control and account for the assets of
the Corporation and provide safeguards therefor, and to collect information
required for management purposes, and shall perform such other duties and have
such other powers as the Board of Directors or the President may designate from
time to time.  The President may direct any Assistant Controller to assume and
perform the duties of the Controller, in the absence or disability of the
Controller, and each Assistant Controller shall perform such other duties and
have such other powers as the Board of Directors, the Chairman of the Board (if
there be such an officer appointed) or the President may designate from time to
time.

                                      ARTICLE V

                       EXECUTION OF CORPORATE INSTRUMENTS, AND
                    VOTING OF SECURITIES OWNED BY THE CORPORATION

    SECTION 1. EXECUTION OF CORPORATE INSTRUMENTS.

         (a)  The Board of Directors may, in its discretion, determine the
method and designate the signatory officer or officers, or other person or
persons, to execute any corporate instrument or document, or to sign the
corporate name without limitation, except where otherwise provided by law, and
such execution or signature shall be binding upon the Corporation.

         (b)  Unless otherwise specifically determined by the Board of
Directors or otherwise required by law, formal contracts of the Corporation,
promissory notes, deeds of trust, mortgages


                                          12

<PAGE>

and other evidences of indebtedness of the Corporation, and other corporate
instruments or documents requiring the corporate seal, and certificates of
shares of stock owned by the Corporation, shall be executed, signed or endorsed
by the Chairman of the Board (if there be such an officer appointed) or by the
President; such documents may also be executed by any Vice-President and by the
Secretary or Treasurer or any Assistant Secretary or Assistant Treasurer.  All
other instruments and documents requiring the corporate signature, but not
requiring the corporate seal, may be executed as aforesaid or in such other
manner as may be directed by the Board of Directors.

         (c)  All checks and drafts drawn on banks or other depositaries on
funds to the credit of the Corporation, or in special accounts of the
Corporation, shall be signed by such person or persons as the Board of Directors
shall authorize so to do.

    SECTION 2. RATIFICATION BY SHAREHOLDERS.  In its discretion, the Board of
Directors may submit any contract or act for approval or ratification of the
shareholders at any annual meeting of shareholders, or at any special meeting of
shareholders called for that purpose; and any contract or act that shall be
approved or ratified by the holders of a majority of the voting power of the
Corporation shall be as valid and binding upon the Corporation and upon the
shareholders thereof as though approved or ratified by each and every
shareholder of the Corporation, unless a greater vote is required by law for
such purpose.

    SECTION 3. VOTING OF SECURITIES OWNED BY CORPORATION.  All stock and other
securities of other Corporations owned or held by the Corporation for itself, or
for other parties in any capacity, shall be voted, and all proxies with respect
thereto shall be executed, by the person authorized so to do by resolution of
the Board of Directors or, in the absence of such authorization, by the Chairman
of the Board (if there be such an officer appointed), or by the President, or by
any Vice-President.

                                      ARTICLE VI

                                   SHARES OF STOCK

    SECTION 1. FORM AND EXECUTION OF CERTIFICATES. Certificates for the shares
of stock of the Corporation shall be in such form as is consistent with the
Certificate of Incorporation and applicable law.  Every holder of stock in the
Corporation shall be entitled to have a certificate signed by, or in the name of
the Corporation by, the Chairman of the Board (if there be such an officer
appointed), or by the President or any Vice-President and by the Treasurer or
Assistant Treasurer or the Secretary or Assistant Secretary, certifying the
number of shares owned by him in the Corporation.  Any or all of the signatures
on the certificate may be a facsimile.  In case any officer, transfer agent, or
registrar who has signed or whose facsimile signature has been placed upon a
certificate shall have ceased to be such officer, transfer agent, or registrar
before such certificate is issued, it may be issued with the same effect as if
he were such officer, transfer agent, or registrar at the date of issue.  If the
Corporation shall be authorized to issue more than one class of stock or more
than one series of any class, the powers, designations, preferences and
relative, participating, optional or other special rights of each class of stock
or series thereof and the qualifications, limitations or restrictions of such
preferences and/or rights shall be set forth in full or


                                          13

<PAGE>

summarized on the face or back of the certificate which the Corporation shall
issue to represent such class or series of stock, provided that, except as
otherwise provided in section 202 of the Delaware General Corporation Law, in
lieu of the foregoing requirements, there may be set forth on the face or back
of the certificate which the Corporation shall issue to represent such class or
series of stock, a statement that the Corporation will furnish without charge to
each stockholder who so requests the powers, designations, preferences and
relative, participating, optional or other special rights of each class of stock
or series thereof and the qualifications, limitations or restrictions of such
preferences and/or rights.

    SECTION 2. LOST CERTIFICATES.  The Board of Directors may direct a new
certificate or certificates to be issued in place of any certificate or
certificates theretofore issued by the Corporation alleged to have been lost or
destroyed, upon the making of an affidavit of that fact by the person claiming
the certificate of stock to be lost or destroyed.  When authorizing such issue
of a new certificate or certificates, the Board of Directors may, in its
discretion and as a condition precedent to the issuance thereof, require the
owner of such lost or destroyed certificate or certificates, or his legal
representative, to indemnify the Corporation in such manner as it shall require
and/or to give the Corporation a surety bond in such form and amount as it may
direct as indemnity against any claim that may be made against the Corporation
with respect to the certificate alleged to have been lost or destroyed.

    SECTION 3. TRANSFERS.  Transfers of record of shares of stock of the
Corporation shall be made only upon its books by the holders thereof, in person
or by attorney duly authorized, and upon the surrender of a certificate or
certificates for a like number of shares, properly endorsed.

    SECTION 4. REGISTERED STOCKHOLDERS.  The Corporation shall be entitled to
recognize the exclusive right of a person registered on its books as the owner
of shares to receive dividends, and to vote as such owner, and shall not be
bound to recognize any equitable or other claim to or interest in such share or
shares on the part of any other person, whether or not it shall have express or
other notice thereof, except as otherwise provided by the laws of Delaware.

                                     ARTICLE VII

                         OTHER SECURITIES OF THE CORPORATION

    All bonds, debentures and other corporate securities of the Corporation,
other than stock certificates, may be signed by the Chairman of the Board (if
there be such an officer appointed), or the President or any Vice-President or
such other person as may be authorized by the Board of Directors and the
corporate seal impressed thereon or a facsimile of such seal imprinted thereon
and attested by the signature of the Secretary or an Assistant Secretary, or the
Treasurer or an Assistant Treasurer; provided, however, that where any such
bond, debenture or other corporate security shall be authenticated by the manual
signature of a trustee under an indenture pursuant to which such bond, debenture
or other corporate security shall be issued, the signature of the persons
signing and attesting the corporate seal on such bond, debenture or other
corporate security may be the imprinted facsimile of the signatures of such
persons.  Interest coupons appertaining to any such bond, debenture or other
corporate security, authenticated by a trustee as aforesaid, shall be signed


                                          14

<PAGE>

by the Treasurer or an Assistant Treasurer of the Corporation, or such other
person as may be authorized by the Board of Directors, or bear imprinted thereon
the facsimile signature of such person.  In case any officer who shall have
signed or attested any bond, debenture or other corporate security, or whose
facsimile signature shall appear thereon or before the bond, debenture or other
corporate security so signed or attested shall have been delivered, such bond,
debenture or other corporate security nevertheless may be adopted by the
Corporation and issued and delivered as though the person who signed the same or
whose facsimile signature shall have been used thereon had not ceased to be such
officer of the Corporation.

                                     ARTICLE VIII

                           INSPECTION OF CORPORATE RECORDS

    SECTION 1. GENERAL RECORDS.  Every director shall have the absolute right
at any reasonable time to inspect and copy all books, records and documents of
every kind and to inspect the physical properties of the Corporation and its
subsidiaries.  Such inspection by a director may be made in person or by agent
or attorney, and the right of inspection includes the right to copy and make
extracts.

    SECTION 2. INSPECTION OF BYLAWS.  The Corporation shall keep at the office
of the Corporation required to be maintained pursuant to Section 2 of Article I
hereof, the original or a copy of these Bylaws as amended to date, which shall
be open to inspection by the stockholders at all reasonable times during office
hours.

                                      ARTICLE IX

             INDEMNIFICATION OF OFFICERS, DIRECTORS, EMPLOYEES AND AGENTS

    SECTION 1. RIGHT TO INDEMNIFICATION.  Each person who was or is a party or
is threatened to be made a party to or is involved (as a party, witness, or
otherwise), in any threatened, pending, or completed action, suit, or
proceeding, whether civil, criminal, administrative, or investigative
(hereinafter a "Proceeding"), by reason of the fact that he, or a person of whom
he is the legal representative, is or was a director, officer, employee, or
agent of the Corporation or is or was serving at the request of the Corporation
as a director, officer, employee, or agent of another Corporation or of a
partnership, joint venture, trust, or other enterprise, including service with
respect to employee benefit plans, whether the basis of the Proceeding is
alleged action in an official capacity as a director, officer, employee, or
agent or in any other capacity while serving as a director, officer, employee,
or agent (hereafter an "Agent"), shall be indemnified and held harmless by the
Corporation to the fullest extent authorized by the Delaware General Corporation
Law, as the same exists or may hereafter be amended or interpreted (but, in the
case of any such amendment or interpretation, only to the extent that such
amendment or interpretation permits the Corporation to provide broader
indemnification rights than were permitted prior thereto) against all expenses,
liability, and loss (including attorneys' fees, judgments, fines, ERISA excise
taxes or penalties, and amounts paid or to be paid in settlement, and any
interest, assessments, or other charges imposed thereon, and any federal, state,
local, or foreign taxes imposed on any Agent as a result of the actual


                                          15

<PAGE>

or deemed receipt of any payments under this Article) reasonably incurred or
suffered by such person in connection with investigating, defending, being a
witness in, or participating in (including on appeal), or preparing for any of
the foregoing in, any Proceeding (hereinafter "Expenses"); PROVIDED, HOWEVER,
that except as to actions to enforce indemnification rights pursuant to
Section 3 of this Article, the Corporation shall indemnify any Agent seeking
indemnification in connection with a Proceeding (or part thereof) initiated by
such person only if the Proceeding (or part thereof) was authorized by the Board
of Directors of the Corporation.  The right to indemnification conferred in this
Article shall be a contract right.

    SECTION 2. AUTHORITY TO ADVANCE EXPENSES.  Expenses incurred by an officer
or director (acting in his capacity as such) in defending a Proceeding shall be
paid by the Corporation in advance of the final disposition of such Proceeding,
PROVIDED, HOWEVER, that if required by the Delaware General Corporation Law, as
amended, such Expenses shall be advanced only upon delivery to the Corporation
of an undertaking by or on behalf of such director or officer to repay such
amount if it shall ultimately be determined that he is not entitled to be
indemnified by the Corporation as authorized in this Article or otherwise.
Expenses incurred by other Agents of the Corporation (or by the directors or
officers not acting in their capacity as such, including service with respect to
employee benefit plans) may be advanced upon such terms and conditions as the
Board of Directors deems appropriate.  Any obligation to reimburse the
Corporation for Expense advances shall be unsecured and no interest shall be
charged thereon.

    SECTION 3. RIGHT OF CLAIMANT TO BRING SUIT.  If a claim under Section 1 or
2 of this Article is not paid in full by the Corporation within 30 days after a
written claim has been received by the Corporation, the claimant may at any time
thereafter bring suit against the Corporation to recover the unpaid amount of
the claim and, if successful in whole or in part, the claimant shall be entitled
to be paid also the expense (including attorneys' fees) of prosecuting such
claim.  It shall be a defense to any such action (other than an action brought
to enforce a claim for expenses incurred in defending a Proceeding in advance of
its final disposition where the required undertaking has been tendered to the
Corporation) that the claimant has not met the standards of conduct that make it
permissible under the Delaware General Corporation Law for the Corporation to
indemnify the claimant for the amount claimed.  The burden of proving such a
defense shall be on the Corporation.  Neither the failure of the Corporation
(including its Board of Directors, independent legal counsel, or its
stockholders) to have made a determination prior to the commencement of such
action that indemnification of the claimant is proper under the circumstances
because he has met the applicable standard of conduct set forth in the Delaware
General Corporation Law, nor an actual determination by the Corporation
(including its Board of Directors, independent legal counsel, or its
stockholders) that the claimant had not met such applicable standard of conduct,
shall be a defense to the action or create a presumption that claimant has not
met the applicable standard of conduct.

    SECTION 4. PROVISIONS NONEXCLUSIVE.  The rights conferred on any person by
this Article shall not be exclusive of any other rights that such person may
have or hereafter acquire under any statute, provision of the Certificate of
Incorporation, agreement, vote of stockholders or disinterested directors, or
otherwise, both as to action in an official capacity and as to action in another
capacity while holding such office.  To the extent that any provision of the
Certificate,


                                          16

<PAGE>

agreement, or vote of the stockholders or disinterested directors is
inconsistent with these Bylaws, the provision, agreement, or vote shall take
precedence.

    SECTION 5. AUTHORITY TO INSURE.  The Corporation may purchase and maintain
insurance to protect itself and any Agent against any Expense, whether or not
the Corporation would have the power to indemnify the Agent against such Expense
under applicable law or the provisions of this Article.

    SECTION 6. SURVIVAL OF RIGHTS.  The rights provided by this Article shall
continue as to a person who has ceased to be an Agent and shall inure to the
benefit of the heirs, executors, and administrators of such a person.

    SECTION 7. SETTLEMENT OF CLAIMS.  The Corporation shall not be liable to
indemnify any Agent under this Article (a) for any amounts paid in settlement of
any action or claim effected without the Corporation's written consent, which
consent shall not be unreasonably withheld; or (b) for any judicial award if the
Corporation was not given a reasonable and timely opportunity, at its expense,
to participate in the defense of such action.

    SECTION 8. EFFECT OF AMENDMENT.  Any amendment, repeal, or modification of
this Article shall not adversely affect any right or protection of any Agent
existing at the time of such amendment, repeal, or modification.

    SECTION 9. SUBROGATION.  In the event of payment under this Article, the
Corporation shall be subrogated to the extent of such payment to all of the
rights of recovery of the Agent, who shall execute all papers required and shall
do everything that may be necessary to secure such rights, including the
execution of such documents necessary to enable the Corporation effectively to
bring suit to enforce such rights.

    SECTION 10. NO DUPLICATION OF PAYMENTS.  The Corporation shall not be
liable under this Article to make any payment in connection with any claim made
against the Agent to the extent the Agent has otherwise actually received
payment (under any insurance policy, agreement, vote, or otherwise) of the
amounts otherwise indemnifiable hereunder.

                                      ARTICLE X

                                       NOTICES

    Whenever, under any provisions of these Bylaws, notice is required to be
given to any stockholder, the same shall be given in writing, timely and duly
deposited in the United States Mail, postage prepaid, and addressed to his last
known post office address as shown by the stock record of the Corporation or its
transfer agent.  Any notice required to be given to any director may be given by
the method hereinabove stated, or by telegram or other means of electronic
transmission, except that such notice other than one which is delivered
personally, shall be sent to such address or (in the case of facsimile
telecommunication) facsimile telephone number as such director shall have filed
in writing with the Secretary of the Corporation, or, in the absence of such
filing, to the last known post office address of such director.  If no address
of a stockholder or director be known,


                                          17

<PAGE>

such notice may be sent to the office of the Corporation required to be
maintained pursuant to Section 2 of Article I hereof.  An affidavit of mailing,
executed by a duly authorized and competent employee of the Corporation or its
transfer agent appointed with respect to the class of stock affected, specifying
the name and address or the names and addresses of the stockholder or
stockholders, director or directors, to whom any such notice or notices was or
were given, and the time and method of giving the same, shall be conclusive
evidence of the statements therein contained.  All notices given by mail, as
above provided, shall be deemed to have been given as at the time of mailing and
all notices given by telegram or other means of electronic transmission shall be
deemed to have been given as at the sending time recorded by the telegraph
company or other electronic transmission equipment operator transmitting the
same.  It shall not be necessary that the same method of giving be employed in
respect of all directors, but one permissible method may be employed in respect
of any one or more, and any other permissible method or methods may be employed
in respect of any other or others.  The period or limitation of time within
which any stockholder may exercise any option or right, or enjoy any privilege
or benefit, or be required to act, or within which any director may exercise any
power or right, or enjoy any privilege, pursuant to any notice sent him in the
manner above provided, shall not be affected or extended in any manner by the
failure of such a stockholder or such director to receive such notice.  Whenever
any notice is required to be given under the provisions of the statutes or of
the Certificate of Incorporation, or of these Bylaws, a waiver thereof in
writing signed by the person or persons entitled to said notice, whether before
or after the time stated therein, shall be deemed equivalent thereto.  Whenever
notice is required to be given, under any provision of law or of the Certificate
of Incorporation or Bylaws of the Corporation, to any person with whom
communication is unlawful, the giving of such notice to such person shall not be
required and there shall be no duty to apply to any governmental authority or
agency for a license or permit to give such notice to such person.  Any action
or meeting which shall be taken or held without notice to any such person with
whom communication is unlawful shall have the same force and effect as if such
notice had been duly given. In the event that the action taken by the
Corporation is such as to require the filing of a certificate under any
provision of the Delaware General Corporation Law, the certificate shall state,
if such is the fact and if notice is required, that notice was given to all
persons entitled to receive notice except such persons with whom communication
is unlawful.

                                      ARTICLE XI

                                      AMENDMENTS

    These Bylaws may be repealed, altered or amended or new Bylaws adopted by
written consent of stockholders in the manner authorized by Section 9 of
Article II, or at any meeting of the stockholders, either annual or special, by
the affirmative vote of a majority of the stock entitled to vote at such
meeting.  The Board of Directors shall also have the authority to repeal, alter
or amend these Bylaws or adopt new Bylaws (including, without limitation, the
amendment of any Bylaws setting forth the number of directors who shall
constitute the whole Board of Directors) by unanimous written consent or at any
annual, regular, or special meeting by the affirmative vote of a majority of the
whole number of directors, subject to the power of the stockholders to change or
repeal such Bylaws.


                                          18

<PAGE>

                                     ARTICLE XII

                                    CORPORATE SEAL

    The corporate seal shall consist of a die bearing the name of the
Corporation and the state and date of its incorporation.  Said seal may be used
by causing it or a facsimile thereof to be impressed or affixed or reproduced or
otherwise.


                                          19


<PAGE>
                                                                    Exhibit 10.1


                              INDEMNIFICATION AGREEMENT



             THIS AGREEMENT is entered into, effective as of ____________, 1996
by and between Progenitor, Inc., a Delaware corporation (the "Company"), and
________________ ("Indemnitee").

             WHEREAS, it is essential to the Company to retain and attract as
directors and officers the most capable persons available;

             WHEREAS, Indemnitee is a director and/or officer of the Company;

             WHEREAS, both the Company and Indemnitee recognize the increased
risk of litigation and other claims currently being asserted against directors
and officers of corporations; and

             WHEREAS, in recognition of Indemnitee's need for substantial
protection against personal liability in order to enhance Indemnitee's continued
and effective service to the Company, and in order to induce Indemnitee to
provide services to the Company as a director and/or officer, the Company wishes
to provide in this Agreement for the indemnification of and the advancing of
expenses to Indemnitee to the fullest extent (whether partial or complete)
permitted by Delaware law and as set forth in this Agreement, and, to the extent
insurance is maintained, for the coverage of Indemnitee under the Company's
directors' and officers' liability insurance policies.

             NOW, THEREFORE, in consideration of the above premises and of
Indemnitee's continuing to serve the Company directly or, at its request, with
another enterprise, and intending to be legally bound hereby, the parties agree
as follows:

             1.     CERTAIN DEFINITIONS:

                    (a)    BOARD:  the Board of Directors of the Company.

                    (b)    CHANGE IN CONTROL:  shall be deemed to have occurred
if (i) any "person" (as such term is used in Sections 13(d) and 14(d) of the
Securities Exchange Act of 1934, as amended (the "Act")), other than Interneuron
Pharmaceuticals, Inc., a trustee or other fiduciary holding securities under an
employee benefit plan of the Company or a corporation owned directly or
indirectly by the stockholders of the Company in substantially the same
proportions as their ownership of stock of the Company, is or becomes the


                                          1

<PAGE>

"Beneficial Owner" (as defined in Rule 13d-3 under the Act), directly or
indirectly, of securities of the Company representing 30% or more of the total
voting power represented by the Company's then outstanding Voting Securities, or
(ii) during any period of two consecutive years, individuals who at the
beginning of such period constitute the Board and any new director whose
election by the Board or nomination for election by the Company's stockholders
was approved by a vote of at least two-thirds (2/3) of the directors then still
in office who either were directors at the beginning of the period or whose
election or nomination for election was previously so approved, cease for any
reason to constitute a majority of the Board, or (iii) the stockholders of the
Company approve a merger or consolidation of the Company with any other
corporation, other than a merger or consolidation that would result in the
Voting Securities of the Company outstanding immediately prior thereto
continuing to represent (either by remaining outstanding or by being converted
into Voting Securities of the surviving entity) at least 50% of the total voting
power represented by the Voting Securities of the Company or such surviving
entity outstanding immediately after such merger or consolidation, or (iv) the
stockholders of the Company approve a plan of complete liquidation of the
Company or an agreement for the sale or disposition by the Company (in one
transaction or a series of transactions) of all or substantially all of the
Company's assets.

                    (c)    EXPENSES:  any expense, liability, or loss,
including attorneys' fees, judgments, fines, ERISA excise taxes and penalties,
amounts paid or to be paid in settlement, any interest, assessments, or other
charges imposed thereon, and any federal, state, local, or foreign taxes imposed
as a result of the actual or deemed receipt of any payments under this
Agreement, paid or incurred in connection with investigating, defending, being a
witness in, or participating in (including on appeal), or preparing for any of
the foregoing in, any Proceeding relating to any Indemnifiable Event.

                    (d)    INDEMNIFIABLE EVENT:  any event or occurrence that
takes place either prior to or after the execution of this Agreement, related to
the fact that Indemnitee is or was a director or an officer of the Company, or
while a director or officer is or was serving at the request of the Company as a
director, officer, employee, trustee, agent, or fiduciary of another foreign or
domestic corporation, partnership, joint venture, employee benefit plan, trust,
or other enterprise, or was a director, officer, employee, or agent of a foreign
or domestic corporation that was a predecessor corporation of the Company or of
another enterprise at the request of such predecessor corporation, or related to
anything done or not done by Indemnitee in any such capacity, whether or not the
basis of the Proceeding is alleged action in an official capacity as a director,
officer, employee, or agent or in any other capacity while serving as a
director, officer, employee, or agent of the Company, as described above.

                    (e)    INDEPENDENT COUNSEL:  the person or body appointed
in connection with Section 3.


                                          2

<PAGE>

                    (f)    POTENTIAL CHANGE IN CONTROL:  shall be deemed to
have occurred if (i) the Company enters into an agreement or arrangement, the
consummation of which would result in the occurrence of a Change in Control;
(ii) any person (including the Company) publicly announces an intention to take
or to consider taking actions that, if consummated, would constitute a Change in
Control; (iii) any person (other than a trustee or other fiduciary holding
securities under an employee benefit plan of the Company acting in such capacity
or a corporation owned, directly or indirectly, by the stockholders of the
Company in substantially the same proportions as their ownership of stock of the
Company), who is or becomes the Beneficial Owner, directly or indirectly, of
securities of the Company representing 10% or more of the combined voting power
of the Company's then outstanding Voting Securities, increases his beneficial
ownership of such securities by 5% or more over the percentage so owned by such
person on the date hereof, or (iv) the Board adopts a resolution to the effect
that, for purposes of this Agreement, a Potential Change in Control has
occurred.

                    (g)    PROCEEDING:  (i) any threatened, pending, or
completed action, suit, or proceeding, whether civil, criminal, administrative,
investigative, or other; or (ii) any inquiry, hearing, or investigation, whether
conducted by the Company or any other party, that Indemnitee in good faith
believes might lead to the institution of any such action, suit, or proceeding.

                    (h)    REVIEWING PARTY:  the person or body appointed in
accordance with Section 3.

                    (i)    VOTING SECURITIES:  any securities of the Company
that vote generally in the election of directors.

             2.     AGREEMENT TO INDEMNIFY.

                    (a)    GENERAL AGREEMENT.  In the event Indemnitee was, is,
or becomes a party to or witness or other participant in, or is threatened to be
made a party to or witness or other participant in, a Proceeding by reason of
(or arising in part out of) an Indemnifiable Event, the Company shall indemnify
Indemnitee from and against any and all Expenses to the fullest extent permitted
by law, as the same exists or may hereafter be amended or interpreted (but in
the case of any such amendment or interpretation, only to the extent that such
amendment or interpretation permits the Company to provide broader
indemnification rights than were permitted prior thereto).  The parties hereto
intend that this Agreement shall provide for indemnification in excess of that
expressly permitted by statute, including, without limitation, any
indemnification provided by the Company's Certificate of Incorporation, its
bylaws, vote of its stockholders or disinterested directors, or applicable law.


                                          3

<PAGE>

                    (b)    INITIATION OF PROCEEDING.  Notwithstanding anything
in this Agreement to the contrary, Indemnitee shall not be entitled to
indemnification pursuant to this Agreement in connection with any Proceeding
initiated by Indemnitee against the Company or any director or officer of the
Company unless (i) the Company has joined in or the Board has consented to the
initiation of such Proceeding; (ii) the Proceeding is one to enforce
indemnification rights under Section 5; or (iii) the Proceeding is instituted
after a Change in Control and Independent Counsel has approved its initiation.

                    (c)    EXPENSE ADVANCES.  If so requested by Indemnitee,
the Company shall advance (within ten business days of such request) any and all
Expenses to Indemnitee (an "Expense Advance"); provided that, if and to the
extent that the Reviewing Party determines that Indemnitee would not be
permitted to be so indemnified under applicable law, the Company shall be
entitled to be reimbursed by Indemnitee (who hereby agrees to reimburse the
Company) for all such amounts theretofore paid.  If Indemnitee has commenced
legal proceedings in a court of competent jurisdiction to secure a determination
that Indemnitee should be indemnified under applicable law, as provided in
Section 4, any determination made by the Reviewing Party that Indemnitee would
not be permitted to be indemnified under applicable law shall not be binding and
Indemnitee shall not be required to reimburse the Company for any Expense
Advance until a final judicial determination is made with respect thereto (as to
which all rights of appeal therefrom have been exhausted or have lapsed).
Indemnitee's obligation to reimburse the Company for Expense Advances shall be
unsecured and no interest shall be charged thereon.

                    (d)    MANDATORY INDEMNIFICATION.  Notwithstanding any
other provision of this Agreement (other than Section 2(f) below), to the extent
that Indemnitee has been successful on the merits in defense of any Proceeding
relating in whole or in part to an Indemnifiable Event or in defense of any
issue or matter therein, Indemnitee shall be indemnified against all Expenses
incurred in connection therewith.

                    (e)    PARTIAL INDEMNIFICATION.  If Indemnitee is entitled
under any provision of this Agreement to indemnification by the Company for some
or a portion of Expenses, but not, however, for the total amount thereof, the
Company shall nevertheless indemnify Indemnitee for the portion thereof to which
Indemnitee is entitled.

                    (f)    PROHIBITED INDEMNIFICATION.  No indemnification
pursuant to this Agreement shall be paid by the Company on account of any
Proceeding in which judgment is rendered against Indemnitee for an accounting of
profits made from the purchase or sale by Indemnitee of securities of the
Company pursuant to the provisions of Section 16(b) of the Act or similar
provisions of any federal, state, or local laws.


                                          4

<PAGE>

             3.     REVIEWING PARTY.  Prior to any Change in Control, the
Reviewing Party shall be any appropriate person or body consisting of a member
or members of the Board or any other person or body appointed by the Board who
is not a party to the particular Proceeding with respect to which Indemnitee is
seeking indemnification; after a Change in Control, the Reviewing Party shall be
the Independent Counsel referred to below.  With respect to all matters arising
after a Change in Control (other than a Change in Control approved by a majority
of the directors on the Board who were directors immediately prior to such
Change in Control) concerning the rights of Indemnitee to indemnity payments and
Expense Advances under this Agreement or any other agreement or under applicable
law or the Company's Certificate of Incorporation or Bylaws now or hereafter in
effect relating to indemnification for Indemnifiable Events, the Company shall
seek legal advice only from Independent Counsel selected by Indemnitee and
approved by the Company (which approval shall not be unreasonably withheld), and
who has not otherwise performed services for the Company or the Indemnitee
(other than in connection with indemnification matters) within the last five
years.  The Independent Counsel shall not include any person who, under the
applicable standards of professional conduct then prevailing, would have a
conflict of interest in representing either the Company or Indemnitee in an
action to determine Indemnitee's rights under this Agreement.  Such counsel,
among other things, shall render its written opinion to the Company and
Indemnitee as to whether and to what extent the Indemnitee should be permitted
to be indemnified under applicable law.  The Company agrees to pay the
reasonable fees of the Independent Counsel and to indemnify fully such counsel
against any and all expenses (including attorneys' fees), claims, liabilities,
loss, and damages arising out of or relating to this Agreement or the engagement
of Independent Counsel pursuant hereto.

             4.     INDEMNIFICATION PROCESS AND APPEAL.

                    (a)    INDEMNIFICATION PAYMENT.  Indemnitee shall be
entitled to indemnification of Expenses, and shall receive payment thereof, from
the Company in accordance with this Agreement as soon as practicable after
Indemnitee has made written demand on the Company for indemnification, unless
the Reviewing Party has given a written opinion to the Company that Indemnitee
is not entitled to indemnification under applicable law.

                    (b)    SUIT TO ENFORCE RIGHTS.  Regardless of any action by
the Reviewing Party, if Indemnitee has not received full indemnification within
thirty days after making a demand in accordance with Section 4(a), Indemnitee
shall have the right to enforce its indemnification rights under this Agreement
by commencing litigation in any court in the State of Ohio having subject matter
jurisdiction thereof and in which venue is proper seeking an initial
determination by the court or challenging any determination by the Reviewing
Party


                                          5

<PAGE>

or any aspect thereof.  The Company hereby consents to service of process and to
appear in any such proceeding.  Any determination by the Reviewing Party not
challenged by the Indemnitee shall be binding on the Company and Indemnitee.
The remedy provided for in this Section 4 shall be in addition to any other
remedies available to Indemnitee in law or equity.

                    (c)    DEFENSE TO INDEMNIFICATION, BURDEN OF PROOF, AND
PRESUMPTIONS.  It shall be a defense to any action brought by Indemnitee against
the Company to enforce this Agreement (other than an action brought to enforce a
claim for Expenses incurred in defending a Proceeding in advance of its final
disposition where the required undertaking has been tendered to the Company)
that it is not permissible under applicable law for the Company to indemnify
Indemnitee for the amount claimed.  In connection with any such action or any
determination by the Reviewing Party or otherwise as to whether Indemnitee is
entitled to be indemnified hereunder, the burden of proving such a defense or
determination shall be on the Company.  Neither the failure of the Reviewing
Party or the Company (including its Board, independent legal counsel, or its
stockholders) to have made a determination prior to the commencement of such
action by Indemnitee that indemnification of the claimant is proper under the
circumstances because Indemnitee has met the standard of conduct set forth in
applicable law, nor an actual determination by the Reviewing Party or Company
(including its Board, independent legal counsel, or its stockholders) that the
Indemnitee had not met such applicable standard of conduct, shall be a defense
to the action or create a presumption that the Indemnitee has not met the
applicable standard of conduct.  For purposes of this Agreement, the termination
of any claim, action, suit, or proceeding, by judgment, order, settlement
(whether with or without court approval), conviction, or upon a plea of nolo
contendere, or its equivalent, shall not create a presumption that Indemnitee
did not meet any particular standard of conduct or have any particular belief or
that a court has determined that indemnification is not permitted by applicable
law.

             5.     INDEMNIFICATION FOR EXPENSES INCURRED IN ENFORCING RIGHTS.
The Company shall indemnify Indemnitee against any and all Expenses and, if
requested by Indemnitee, shall (within ten business days of such request),
advance such Expenses to Indemnitee, that are incurred by Indemnitee in
connection with any claim asserted against or action brought by Indemnitee for

                    (i)    indemnification of Expenses or Expense Advances by
the Company under this Agreement or any other agreement or under applicable law
or the Company's Certificate of Incorporation or Bylaws now or hereafter in
effect relating to indemnification for Indemnifiable Events, and/or

                    (ii)   recovery under directors' and officers' liability
insurance policies maintained by the Company,


                                          6

<PAGE>

regardless of whether Indemnitee ultimately is determined to be entitled to such
indemnification, Expense Advances, or insurance recovery, as the case may be.

             6.     NOTIFICATION AND DEFENSE OF PROCEEDING.

                    (a)    NOTICE.  Promptly after receipt by Indemnitee of
notice of the commencement of any Proceeding, Indemnitee shall, if a claim in
respect thereof is to be made against the Company under this Agreement, notify
the Company of the commencement thereof; but the omission so to notify the
Company will not relieve the Company from any liability that it may have to
Indemnitee, except as provided in Section 6(c).

                    (b)    DEFENSE.  With respect to any Proceeding as to which
Indemnitee notifies the Company of the commencement thereof, the Company shall
be entitled to participate in the Proceeding at its own expense and except as
otherwise provided below, to the extent the Company so wishes, it may assume the
defense thereof with counsel reasonably satisfactory to Indemnitee.  After
notice from the Company to Indemnitee of its election to assume the defense of
any Proceeding, the Company shall not be liable to Indemnitee under this
Agreement or otherwise for any Expenses subsequently incurred by Indemnitee in
connection with the defense of such Proceeding other than reasonable costs of
investigation or as otherwise provided below.  Indemnitee shall have the right
to employ his or her own legal counsel in such Proceeding, but all Expenses
related thereto incurred after notice from the Company of its assumption of the
defense shall be at Indemnitee's expense unless:  (i) the employment of legal
counsel by Indemnitee has been authorized by the Company, (ii) Indemnitee has
reasonably determined that there may be a conflict of interest between
Indemnitee and the Company in the defense of the Proceeding, (iii) after a
Change in Control, the employment of counsel by Indemnitee has been approved by
the Independent Counsel, or (iv) the Company shall not in fact have employed
counsel to assume the defense of such Proceeding, in each of which case all
Expenses of the Proceeding shall be borne by the Company.  The Company shall not
be entitled to assume the defense of any Proceeding brought by or on behalf of
the Company or as to which Indemnitee shall have made the determination provided
for in (ii) above.

                    (c)    SETTLEMENT OF CLAIMS.  The Company shall not be
liable to indemnify Indemnitee under this Agreement or otherwise for any amounts
paid in settlement of any Proceeding effected without the Company's written
consent, provided, however, that if a Change in Control has occurred, the
Company shall be liable for indemnification of Indemnitee for amounts paid in
settlement if the Independent Counsel has approved the settlement.  The Company
shall not settle any Proceeding in any manner that would impose any penalty or
limitation on Indemnitee without Indemnitee's written consent.  Neither the


                                          7

<PAGE>

Company nor the Indemnitee will unreasonably withhold their consent to any
proposed settlement.  The Company shall not be liable to indemnify the
Indemnitee under this Agreement with regard to any judicial award if the Company
was not given a reasonable and timely opportunity, at its expense, to
participate in the defense of such action; the Company's liability hereunder
shall not be excused if participation in the Proceeding by the Company was
barred by this Agreement.

             7.     ESTABLISHMENT OF TRUST.  In the event of a Change in
Control or a Potential Change in Control, the Company shall, upon written
request by Indemnitee, create a Trust for the benefit of the Indemnitee and from
time to time upon written request of Indemnitee shall fund the Trust in an
amount sufficient to satisfy any and all Expenses reasonably anticipated at the
time of each such request to be incurred in connection with investigating,
preparing for, participating in, and/or defending any Proceeding relating to an
Indemnifiable Event.  The amount or amounts to be deposited in the Trust
pursuant to the foregoing funding obligation shall be determined by the
Reviewing Party.  The terms of the Trust shall provide that upon a Change in
Control, (i) the Trust shall not be revoked or the principal thereof invaded,
without the written consent of the Indemnitee, (ii) the Trustee shall advance,
within ten business days of a request by the Indemnitee, any and all Expenses to
the Indemnitee (and the Indemnitee hereby agrees to reimburse the Trust under
the same circumstances for which the Indemnitee would be required to reimburse
the Company under Section 2(c) of this Agreement), (iii) the Trust shall
continue to be funded by the Company in accordance with the funding obligation
set forth above, (iv) the Trustee shall promptly pay to the Indemnitee all
amounts for which the Indemnitee shall be entitled to indemnification pursuant
to this Agreement or otherwise, and (v) all unexpended funds in the Trust shall
revert to the Company upon a final determination by the Reviewing Party or a
court of competent jurisdiction, as the case may be, that the Indemnitee has
been fully indemnified under the terms of this Agreement.  The Trustee shall be
chosen by the Indemnitee.  Nothing in this Section 7 shall relieve the Company
of any of its obligations under this Agreement.  All income earned on the assets
held in the Trust shall be reported as income by the Company for federal, state,
local, and foreign tax purposes.  The Company shall pay all costs of
establishing and maintaining the Trust and shall indemnify the Trustee against
any and all expenses (including attorneys' fees), claims, liabilities, loss, and
damages arising out of or relating to this Agreement or the establishment and
maintenance of the Trust.

             8.     NON-EXCLUSIVITY.  The rights of Indemnitee hereunder shall
be in addition to any other rights Indemnitee may have under the Company's
Certificate of Incorporation, Bylaws, applicable law, or otherwise.  To the
extent that a change in applicable law (whether by statute or judicial decision)
permits greater indemnification by agreement than would be afforded currently
under the Company's Certificate of Incorporation, Bylaws,


                                          8

<PAGE>

applicable law, or this Agreement, it is the intent of the parties that
Indemnitee enjoy by this Agreement the greater benefits so afforded by such
change.
             9.     LIABILITY INSURANCE.  To the extent the Company maintains
an insurance policy or policies providing directors' and officers' liability
insurance, Indemnitee shall be covered by such policy or policies, in accordance
with its or their terms, to the maximum extent of the coverage available for any
Company director or officer.

             10.    PERIOD OF LIMITATIONS.  No legal action shall be brought
and no cause of action shall be asserted by or on behalf of the Company or any
affiliate of the Company against Indemnitee, Indemnitee's spouse, heirs,
executors, or personal or legal representatives after the expiration of two
years from the date of accrual of such cause of action, or such longer period as
may be required by state law under the circumstances.  Any claim or cause of
action of the Company or its affiliate shall be extinguished and deemed released
unless asserted by the timely filing of a legal action within such period;
provided, however, that if any shorter period of limitations is otherwise
applicable to any such cause of action the shorter period shall govern.

             11.    AMENDMENT OF THIS AGREEMENT.  No supplement, modification,
or amendment of this Agreement shall be binding unless executed in writing by
both of the parties hereto.  No waiver of any of the provisions of this
Agreement shall operate as a waiver of any other provisions hereof (whether or
not similar), nor shall such waiver constitute a continuing waiver.  Except as
specifically provided herein, no failure to exercise or any delay in exercising
any right or remedy hereunder shall constitute a waiver thereof.

             12.    SUBROGATION.  In the event of payment under this
Agreement, the Company shall be subrogated to the extent of such payment to all
of the rights of recovery of Indemnitee, who shall execute all papers required
and shall do everything that may be necessary to secure such rights, including
the execution of such documents necessary to enable the Company effectively to
bring suit to enforce such rights.

             13.    NO DUPLICATION OF PAYMENTS.  The Company shall not be
liable under this Agreement to make any payment in connection with any claim
made against Indemnitee to the extent Indemnitee has otherwise received payment
(under any insurance policy, Bylaw, or otherwise) of the amounts otherwise
indemnifiable hereunder.

             14.    BINDING EFFECT.  This Agreement shall be binding upon and
inure to the benefit of and be enforceable by the parties hereto and their
respective successors (including any direct or indirect successor by purchase,
merger, consolidation, or otherwise to all or substantially all of the business
and/or assets of the Company), assigns, spouses, heirs, and


                                          9

<PAGE>

personal and legal representatives.  The Company shall require and cause any
successor (whether direct or indirect by purchase, merger, consolidation, or
otherwise) to all, substantially all, or a substantial part, of the business
and/or assets of the Company, by written agreement in form and substance
satisfactory to Indemnitee, expressly to assume and agree to perform this
Agreement in the same manner and to the same extent that the Company would be
required to perform if no such succession had taken place.  The indemnification
provided under this Agreement shall continue as to Indemnitee for any action
taken or not taken while serving in an indemnified capacity pertaining to an
Indemnifiable Event even though he or she may have ceased to serve in such
capacity at the time of any Proceeding.

             15.    SEVERABILITY.  If any provision (or portion thereof) of
this Agreement shall be held by a court of competent jurisdiction to be invalid,
void, or otherwise unenforceable, the remaining provisions shall remain
enforceable to the fullest extent permitted by law.  Furthermore, to the fullest
extent possible, the provisions of this Agreement (including, without
limitation, each portion of this Agreement containing any provision held to be
invalid, void, or otherwise unenforceable, that is not itself invalid, void, or
unenforceable) shall be construed so as to give effect to the intent manifested
by the provision held invalid, void, or unenforceable.

             16.    GOVERNING LAW.  This Agreement shall be governed by and
construed and enforced in accordance with the laws of the State of Delaware
applicable to contracts made and to be performed in such State without giving
effect to the principles of conflicts of laws.

             17.    NOTICES.  All notices, demands, and other communications
required or permitted hereunder shall be made in writing and shall be deemed to
have been duly given if delivered by hand, against receipt, or mailed, postage
prepaid, certified or registered mail, return receipt requested, and addressed
to the Company at:

                    Progenitor, Inc.
                    1507 Chamber Road
                    Columbus, Ohio  43212
                    Attention:  President

                    Notice of change of address shall be effective only when
given in accordance with this Section.  All notices complying with this Section
shall be deemed to have been received on the date of delivery or on the third
business day after mailing.

             18.    COUNTERPARTS.  This Agreement may be executed in one or
more counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.


                                          10

<PAGE>

             IN WITNESS WHEREOF, the parties hereto have duly executed and
delivered this Agreement as of the day specified above.

                                       PROGENITOR, INC.



                                       By:
                                          -----------------------------------

                                       Title:
                                             --------------------------------


                                       INDEMNITEE:



                                       --------------------------------------
                                       [Indemnitee]


                                          11

<PAGE>
                                                                   Exhibit 10.5


                                PROGENITOR, INC.

                            1996 STOCK INCENTIVE PLAN

     1.   PURPOSES OF THE PLAN.  The purposes of this Stock Incentive Plan are
to attract and retain the best available personnel for positions of substantial
responsibility, to provide additional incentive to Employees, Directors and
Consultants of the Company and its Subsidiaries and to promote the success of
the Company's business.

     2.   DEFINITIONS.  As used herein, the following definitions shall apply:

          (a)  "ADMINISTRATOR" means the Board or any of the Committees
appointed to administer the Plan.

          (b)  "AFFILIATE" and "ASSOCIATE" shall have the respective meanings
ascribed to such terms in Rule 12b-2 promulgated under the Exchange Act.

          (c)  "APPLICABLE LAWS" means the legal requirements relating to the
administration of stock incentive plans, if any, under applicable provisions of
federal securities laws, state corporate and securities laws, the Code, and the
rules of any applicable stock exchange or national market system.

          (d)  "AWARD" means the grant of an Option, SAR, Dividend Equivalent
Right, Restricted Stock, Performance Unit, Performance Share, or other right or
benefit under the Plan.

          (e)  "AWARD AGREEMENT" means the written agreement evidencing the
grant of an Award executed by the Company and the Grantee, including any
amendments thereto.

          (f)  "BOARD" means the Board of Directors of the Company.

          (g)  "CHANGE IN CONTROL" shall mean a change in ownership or control
of the Company effected through either of the following transactions:

               (i)  the direct or indirect acquisition by any person or related
group of persons (other than an acquisition from or by the Company or by a
Company-sponsored employee benefit plan or by a person that directly or
indirectly controls, is controlled by, or is under common control with, the
Company) of beneficial ownership (within the meaning of Rule 13d-3 of the
Exchange Act) of securities possessing more than fifty percent (50%) of the
total combined voting power of the Company's outstanding securities pursuant to
a tender or exchange offer made directly to the Company's stockholders which a
majority of the Continuing Directors who are not Affiliates or Associates of the
offeror do not recommend such stockholders to accept, or

               (ii) a change in the composition of the Board over a period of
thirty-six (36) months or less such that a majority of the Board members
(rounded up to the next whole


                                        1
<PAGE>


number) ceases, by reason of one or more contested elections for Board
membership, to be comprised of individuals who are Continuing Directors.

          (h)  "CODE" means the Internal Revenue Code of 1986, as amended.

          (i)  "COMMITTEE" means any committee appointed by the Board to
administer the Plan.

          (j)  "COMMON STOCK" means the common stock of the Company, as adjusted
in accordance with the provisions of Section 10, below.

          (k)  "COMPANY" means Progenitor, Inc., a Delaware corporation.

          (l)  "CONSULTANT" means any person who is engaged by the Company or
any Parent or Subsidiary to render consulting or advisory services and is
compensated for such services.

          (m)  "CONTINUING DIRECTORS" shall mean members of the Board who either
(i) have been Board members continuously for a period of at least thirty-six
(36) months or (ii) have been Board members for less than thirty-six (36) months
and were elected or nominated for election as Board members by at least a
majority of the Board members described in clause (i) who were still in office
at the time such election or nomination was approved by the Board.

          (n)  "CONTINUOUS STATUS AS AN EMPLOYEE, DIRECTOR OR CONSULTANT" means
that the employment, director or consulting relationship with the Company, any
Parent, or Subsidiary, is not interrupted or terminated.  Continuous Status as
an Employee, Director or Consultant shall not be considered interrupted in the
case of (i) any leave of absence approved by the Company or (ii) transfers
between locations of the Company or between the Company, its Parent, any
Subsidiary, or any successor.  A leave of absence approved by the Company shall
include sick leave, military leave, or any other personal leave approved by an
authorized representative of the Company.  For purposes of Incentive Stock
Options, no such leave may exceed 90 days, unless reemployment upon expiration
of such leave is guaranteed by statute or contract.

          (o)  "CORPORATE TRANSACTION" means any of the following stockholder-
approved transactions to which the Company is a party:

               (i)  a merger or consolidation in which the Company is not the
surviving entity, except for a transaction the principal purpose of which is to
change the state in which the Company is incorporated,

               (ii) the sale, transfer or other disposition of all or
substantially all of the assets of the Company (including the capital stock of
the Company's subsidiary corporations) in connection with complete liquidation
or dissolution of the Company, or


                                        2
<PAGE>


               (iii)     any reverse merger in which the Company is the
surviving entity but in which securities possessing more than fifty percent
(50%) of the total combined voting power of the Company's outstanding securities
are transferred to a person or persons different from those who held such
securities immediately prior to such merger.

          (p)  "DIRECTOR" means a member of the Board.

          (q)  "DIVIDEND EQUIVALENT RIGHT" means a right entitling the Grantee
to compensation measured by dividends paid with respect to Common Stock.

          (r)  "EMPLOYEE" means any person, including Officers and Directors,
employed by the Company or any Parent or Subsidiary of the Company.  The payment
of a director's fee by the Company shall not be sufficient to constitute
"employment" by the Company.

          (s)  "EXCHANGE ACT" means the Securities Exchange Act of 1934, as
amended.

          (t)  "FAIR MARKET VALUE" means, as of any date, the value of Common
Stock determined as follows:

               (i)  Where there exists a public market for the Common Stock, the
Fair Market Value shall be (A) the closing sales price for a Share for the last
market trading day prior to the time of the determination (or, if no sales were
reported on that date, on the last trading date on which sales were reported) on
the New York Stock Exchange, the Nasdaq National Market or the principal
securities exchange on which the Common Stock is listed for trading, whichever
is applicable or (B) if the Common Stock is not traded on any such exchange or
national market system, the average of the closing bid and asked prices of a
Share on the Nasdaq Small Cap Market, in each case, as reported in THE WALL
STREET JOURNAL or such other source as the Administrator deems reliable; or

               (ii) In the absence of an established market of the type
described in (i), above, for the Common Stock, the Fair Market Value thereof
shall be determined by the Administrator in good faith, and such determination
shall be conclusive and binding on all persons.

          (u)  "GRANTEE" means an Employee, Director or Consultant who receives
an Award under the Plan.

          (v)  "INCENTIVE STOCK OPTION" means an Option intended to qualify as
an incentive stock option within the meaning of Section 422 of the Code.

          (w)  "NON-QUALIFIED STOCK OPTION" means an Option not intended to
qualify as an Incentive Stock Option.


                                        3
<PAGE>


          (x)  "OFFICER" means a person who is an officer of the Company within
the meaning of Section 16 of the Exchange Act and the rules and regulations
promulgated thereunder.

          (y)  "OPTION" means a stock option granted pursuant to the Plan.

          (z)  "OPTIONED STOCK" means the Common Stock subject to an Option or
other Award.

          (aa) "PARENT" means a "parent corporation," whether now or hereafter
existing, as defined in Section 424(e) of the Code.

          (bb) "PERFORMANCE SHARES" means Shares or an Award denominated in
Shares which may be earned in whole or in part upon attainment of performance
criteria established by the Administrator.

          (cc) "PERFORMANCE UNITS" means monetary awards which may be earned in
whole or in part upon attainment of performance criteria established by the
Administrator.

          (dd) "PLAN" means this 1996 Stock Incentive Plan.

          (ee) "RESTRICTED STOCK" means Shares issued under the Plan to the
Grantee for such consideration, if any, and subject to such restrictions on
transfer, rights of first refusal, repurchase provisions, forfeiture provisions,
and other terms and conditions as established by the Administrator.

          (ff) "RULE 16b-3" means Rule 16b-3 promulgated under the Exchange Act
or any successor thereto.

          (gg) "SAR" means a stock appreciation right entitling the Grantee to
Shares or cash compensation measured by appreciation in the value of Common
Stock.

          (hh) "SHARE" means a share of the Common Stock.

          (ii) "SUBSIDIARY" means a "subsidiary corporation," whether now or
hereafter existing, as defined in Section 424(f) of the Code.

          (jj) "SUBSIDIARY DISPOSITION" means the disposition by the Company of
its equity holdings in any subsidiary corporation effected by a merger or
consolidation involving that subsidiary corporation, the sale of all or
substantially all of the assets of that subsidiary corporation or the Company's
sale or distribution of substantially all of the outstanding capital stock of
such subsidiary corporation.

     3.   STOCK SUBJECT TO THE PLAN.

          (a)  Subject to the provisions of Section 10, below, the maximum
aggregate number of Shares which may be issued pursuant to all Awards (including
Incentive Stock


                                        4
<PAGE>


Options) is 1,550,000 Shares.  The Shares may be authorized, but unissued, or
reacquired Common Stock.

          (b)  If an Award expires or becomes unexercisable without having been
exercised in full, or is surrendered pursuant to an Award exchange program, or
if any unissued Shares are retained by the Company upon exercise of an Award in
order to satisfy the exercise price for such Award or any withholding taxes due
with respect to such Award, such unissued or retained Shares shall become
available for future grant or sale under the Plan (unless the Plan has
terminated).  Shares that actually have been issued under the Plan pursuant to
an Award shall not be returned to the Plan and shall not become available for
future distribution under the Plan, except that if unvested Shares are
forfeited, or repurchased by the Company at their original purchase price, such
Shares shall become available for future grant under the Plan.

     4.   ADMINISTRATION OF THE PLAN.

          (a)  PLAN ADMINISTRATOR.

               (i)  ADMINISTRATION WITH RESPECT TO DIRECTORS AND OFFICERS.  With
respect to grants of Awards to Directors or Employees who are also Officers or
Directors of the Company, the Plan shall be administered by (A) the Board or
(B) a Committee designated by the Board, which Committee shall be constituted in
such a manner as to satisfy the Applicable Laws and to permit such grants and
related transactions under the Plan to be exempt from Section 16(b) of the
Exchange Act in accordance with Rule 16b-3.  Once appointed, such Committee
shall continue to serve in its designated capacity until otherwise directed by
the Board.

               (ii) ADMINISTRATION WITH RESPECT TO CONSULTANTS AND OTHER
EMPLOYEES.  With respect to grants of Awards to Employees or Consultants who are
neither Directors nor Officers of the Company, the Plan shall be administered by
(A) the Board or (B) a Committee designated by the Board, which Committee shall
be constituted in such a manner as to satisfy the Applicable Laws.  Once
appointed, such Committee shall continue to serve in its designated capacity
until otherwise directed by the Board.  The Board may authorize one or more
Officers to grant such Awards and may limit such authority by requiring that
such Awards must be reported to and ratified by the Board or a Committee within
six (6) months of the grant date, and if so ratified, shall be effective as of
the grant date.

          (b)  POWERS OF THE ADMINISTRATOR.  Subject to Applicable Laws, the
provisions of the Plan (including any other powers given to the Administrator
hereunder) and except as otherwise provided by the Board, the Administrator
shall have the authority, in its discretion:

               (i)  to select the Employees, Directors and Consultants to whom
Awards may from time to time be granted hereunder;

               (ii) to determine whether and to what extent Awards are granted
hereunder;


                                        5
<PAGE>


               (iii)     to determine the number of Shares to be covered by each
Award granted hereunder;

               (iv) to approve forms of Award Agreement for use under the Plan;

               (v)  to determine the terms and conditions of any Award granted
hereunder;

               (vi) to amend the terms of any outstanding Award granted under
the Plan including a reduction in the exercise price (or base amount on which
appreciation is measured) of any Award to reflect a reduction in the Fair Market
Value of the Common Stock since the grant date of the Award, provided that any
amendment that would adversely affect the Grantee's rights under an outstanding
Award shall not be made without the Grantee's written consent;

               (vii)     to construe and interpret the terms of the Plan and
Awards granted pursuant to the Plan; and

               (viii)    to take such other action, not inconsistent with the
terms of the Plan, as the Administrator deems appropriate.

          (c)  EFFECT OF ADMINISTRATOR'S DECISION.  All decisions,
determinations and interpretations of the Administrator shall be final and
binding on the Grantees and any other holders of Awards intended by the
Administrator to be affected thereby.

     5.   ELIGIBILITY.  Awards other than Incentive Stock Options may be granted
to Employees, Directors and Consultants.  Incentive Stock Options may be granted
only to Employees.  An Employee, Director or Consultant who has been granted an
Award may, if otherwise eligible, be granted additional Awards.  Awards may be
granted to such Employees of the Company and its subsidiaries who are residing
in foreign jurisdictions as the Administrator in its sole discretion may
determine from time to time.  The Administrator may establish additional terms,
conditions, rules or procedures to accommodate the rules or laws of applicable
foreign jurisdictions and to afford Grantees favorable treatment under such
laws; provided, however, that no Award shall be granted under any such
additional terms, conditions, rules or procedures with terms or conditions which
are inconsistent with the provisions of the Plan.

     6.   TERMS AND CONDITIONS OF AWARDS.

          (a)  TYPE OF AWARDS.  The Administrator is authorized under the Plan
to award any type of arrangement to an Employee, Director or Consultant that is
not inconsistent with the provisions of the Plan and that by its terms involves
or might involve the issuance of (i) Shares, (ii) an Option, a SAR or similar
right with an exercise or conversion privilege at a fixed or variable price
related to the Common Stock and/or the passage of time, the occurrence of one or
more events, or the satisfaction of performance criteria or other conditions, or
(iii) any other security with the value derived from the value of the Common
Stock. Such awards include, without limitation, Options, SARs, sales or bonuses
of Restricted Stock, Dividend Equivalent


                                        6
<PAGE>


Rights, Performance Units or Performance Shares, and an Award may consist of one
such security or benefit, or two or more of them in any combination or
alternative.

          (b)  DESIGNATION OF AWARD.  Each Award shall be designated in the
Award Agreement.  In the case of an Option, the Option shall be designated as
either an Incentive Stock Option or a Non-Qualified Stock Option.  However,
notwithstanding such designation, to the extent that the aggregate Fair Market
Value of Shares subject to Options designated as Incentive Stock Options which
become exercisable for the first time by a Grantee during any calendar year
(under all plans of the Company or any Parent or Subsidiary) exceeds $100,000,
such excess Options, to the extent of the Shares covered thereby in excess of
the foregoing limitation,  shall be treated as Non-Qualified Stock Options.  For
this purpose, Incentive Stock Options shall be taken into account in the order
in which they were granted, and the Fair Market Value of the Shares shall be
determined as of the date the Option with respect to such Shares is granted.

          (c)  CONDITIONS OF AWARD.  Subject to the terms of the Plan, the
Administrator shall determine the provisions, terms, and conditions of each
Award including, but not limited to, the Award vesting schedule, repurchase
provisions, rights of first refusal, forfeiture provisions, form of payment
(cash, Shares, or other consideration) upon settlement of the Award, payment
contingencies, and satisfaction of any performance criteria.  The performance
criteria established by the Administrator may be based on any one of, or
combination of, increase in share price, earnings per share, total shareholder
return, return on equity, return on assets, return on investment, net operating
income, cash flow, revenue, economic value added, personal management
objectives, or other measure of performance selected by the Administrator.
Partial achievement of the specified criteria may result in a payment or vesting
corresponding to the degree of achievement as specified in the Award Agreement.

          (d)  TERM OF AWARD.  The term of each Award shall be the term stated
in the Award Agreement, provided, however, that the term of an Incentive Stock
Option shall be no more than ten (10) years from the date of grant thereof.
However, in the case of an Incentive Stock Option granted to a Grantee who, at
the time the Option is granted, owns stock representing more than ten percent
(10%) of the voting power of all classes of stock of the Company or any Parent
or Subsidiary, the term of the Incentive Stock Option shall be five (5) years
from the date of grant thereof or such shorter term as may be provided in the
Award Agreement.

          (e)  TRANSFERABILITY OF AWARDS.  Incentive Stock Options may not be
sold, pledged, assigned, hypothecated, transferred, or disposed of in any manner
other than by will or by the laws of descent or distribution and may be
exercised, during the lifetime of the Grantee, only by the Grantee.  Other
Awards shall be transferable to the extent provided in the Award Agreement.

          (f)  TIME OF GRANTING AWARDS.  The date of grant of an Award shall for
all purposes be the date on which the Administrator makes the determination to
grant such Award, or such other date as is determined by the Administrator.
Notice of the grant determination shall


                                        7
<PAGE>


be given to each Employee, Director or Consultant to whom an Award is so granted
within a reasonable time after the date of such grant.

     7.   AWARD EXERCISE OR PURCHASE PRICE, CONSIDERATION, TAXES AND RELOAD
     OPTIONS.

          (a)  EXERCISE OR PURCHASE PRICE.  The exercise or purchase price, if
any, for an Award shall be as follows:

               (i)  In the case of an Incentive Stock Option:

                     (A) granted to an Employee who, at the time of the grant of
such Incentive Stock Option owns stock representing more than 10% of the voting
power of all classes of stock of the Company or any Parent or Subsidiary, the
per Share exercise price shall be not less than 110% of the Fair Market Value
per Share on the date of grant.

                     (B) granted to any Employee other than an Employee
described in the preceding paragraph, the per Share exercise price shall be not
less than 100% of the Fair Market Value per Share on the date of grant.

               (ii) In the case of a Non-Qualified Stock Option, the per Share
exercise price shall be not less than 85% of the Fair Market Value per Share on
the date of grant unless otherwise determined by the Administrator.

               (iii)     In the case of other Awards, such price as is
determined by the Administrator.

          (b)  CONSIDERATION.  Subject to Applicable Laws, the consideration to
be paid for the Shares to be issued upon exercise or purchase of an Award
including the method of payment, shall be determined by the Administrator (and,
in the case of an Incentive Stock Option, shall be determined at the time of
grant).  In  addition to any other types of consideration the Administrator may
determine, the Administrator is authorized to accept as consideration for Shares
under the Plan the following:

               (i)    cash;

               (ii)   check;

               (iii)  delivery of Grantee's promissory note with such recourse,
interest, security, and redemption provisions as the Administrator in its
discretion determines as appropriate;

               (iv)   surrender of  Shares (including withholding of Shares
otherwise deliverable upon exercise of the Award) which have a Fair Market Value
on the date of surrender equal to the aggregate exercise price of the Shares as
to which said Award shall be exercised (but only to the extent that such
exercise of the Award would not result in an accounting compensation charge with
respect to the Shares used to pay the exercise price unless otherwise determined
by the Administrator);


                                        8
<PAGE>


               (v)    delivery of a properly executed exercise notice together
with such other documentation as the Administrator and the broker, if
applicable, shall require to effect an exercise of the Award and delivery to the
Company of the sale or loan proceeds required to pay the exercise price; or

               (vi)   any combination of the foregoing methods of payment.

In making its determination as to the type of consideration to accept, the
Administrator shall consider if acceptance of such consideration may be
reasonably expected to benefit the Company.

          (c)  TAXES.  No Shares shall be delivered under the Plan to any
Grantee or other person until such Grantee or other person has made arrangements
acceptable to the Administrator for the satisfaction of federal, state, and
local income and employment tax withholding obligations, including, without
limitation, obligations incident to the receipt of Shares or the disqualifying
disposition of Shares received on exercise of an Incentive Stock Option. Upon
exercise of an Award, the Company shall withhold from Grantee an amount
sufficient to satisfy such tax obligations.

          (d)  RELOAD OPTIONS.  In the event the exercise price or tax
withholding of an Option is satisfied by the Company or the Grantee's employer
withholding Shares otherwise deliverable to the Grantee, the Administrator may
issue the Grantee an additional Option, with terms identical to the Award
Agreement under which the Option was exercised, but at an exercise price as
determined by the Administrator in accordance with the Plan.

     8.   EXERCISE OF AWARD.

          (a)  PROCEDURE FOR EXERCISE; RIGHTS AS A SHAREHOLDER.

               (i)    Any Award granted hereunder shall be exercisable at such
times and under such conditions as determined by the Administrator under the
terms of the Plan and specified in the Award Agreement.

               (ii)   An Award shall be deemed to be exercised when written
notice of such exercise has been given to the Company in accordance with the
terms of the Award by the person entitled to exercise the Award and full payment
for the Shares with respect to which the Award is exercised has been received by
the Company.  Until the issuance (as evidenced by the appropriate entry on the
books of the Company or of a duly authorized transfer agent of the Company) of
the stock certificate evidencing such Shares, no right to vote or receive
dividends or any other rights as a shareholder shall exist with respect to
Optioned Stock, notwithstanding the exercise of an Option or other Award.  The
Company shall issue (or cause to be issued) such stock certificate promptly upon
exercise of the Award.  No adjustment will be made for a dividend or other right
for which the record date is prior to the date the stock certificate is issued,
except as provided in the Award Agreement or Section 10, below.


                                        9
<PAGE>


          (b)  EXERCISE OF AWARD FOLLOWING TERMINATION OF EMPLOYMENT, DIRECTOR
OR CONSULTING RELATIONSHIP.

               (i)    An Award may not be exercised after the termination date
of such Award set forth in the Award Agreement and may be exercised following
the termination of a Grantee's Continuous Status as an Employee, Director or
Consultant only to the extent provided in the Award Agreement.

               (ii)   Where the Award Agreement permits a Grantee to exercise an
Award following the termination of the Grantee's Continuous Status as an
Employee, Director or Consultant for a specified period, the Award shall
terminate to the extent not exercised on the last day of the specified period or
the last day of the original term of the Award whichever occurs first.

               (iii)  Any Award designated as an Incentive Stock Option to the
extent not exercised within the time permitted by law for the exercise of
Incentive Stock Options following the termination of a Grantee's Continuous
Status as an Employee, Director or Consultant shall convert automatically to a
Non-Qualified Stock Option and thereafter shall be exercisable as such to the
extent exercisable by its terms for the period specified in the Award Agreement.

          (c)  BUYOUT PROVISIONS.  The Administrator may at any time offer to
buy out for a payment in cash or Shares, an Award previously granted, based on
such terms and conditions as the Administrator shall establish and communicate
to the Grantee at the time that such offer is made.

     9.   CONDITIONS UPON ISSUANCE OF SHARES.

     (a)  Shares shall not be issued pursuant to the exercise of an Award unless
the exercise of such Award and the issuance and delivery of such Shares pursuant
thereto shall comply with all Applicable Laws, and shall be further subject to
the approval of counsel for the Company with respect to such compliance.

     (b)  As a condition to the exercise of an Award, the Company may require
the person exercising such Award to represent and warrant at the time of any
such exercise that the Shares are being purchased only for investment and
without any present intention to sell or distribute such Shares if, in the
opinion of counsel for the Company, such a representation is required by any
Applicable Laws.

     10.  ADJUSTMENTS UPON CHANGES IN CAPITALIZATION.  Subject to any required
action by the shareholders of the Company, the number of Shares covered by each
outstanding Award, and the number of Shares which have been authorized for
issuance under the Plan but as to which no Awards have yet been granted or which
have been returned to the Plan, as well as the price per share of Common Stock
covered by each such outstanding Award, shall be proportionately adjusted for
any increase or decrease in the number of issued shares of Common Stock
resulting from a stock split, reverse stock split, stock dividend, combination
or reclassification of the



                                       10
<PAGE>


Common Stock, or any other similar event resulting in an increase or decrease in
the number of issued shares of Common Stock.  Such adjustment shall be made by
the Administrator, and its determination in that respect shall be final, binding
and conclusive.  Except as expressly provided herein, no issuance by the Company
of shares of stock of any class, or securities convertible into shares of stock
of any class, shall affect, and no adjustment by reason hereof shall be made
with respect to, the number or price of Shares subject to an Award.

     11.  CORPORATE TRANSACTIONS/CHANGES IN CONTROL/SUBSIDIARY DISPOSITIONS.

   
          (a)  Should any Corporate Transaction occur while an Grantee's
Continuous Status as an Employee, Director or Consultant has not terminated,
then each outstanding Award held by such Grantee, shall become fully vested 
and exercisable and be released from any restrictions on transfer and 
repurchase or forfeiture rights, immediately prior to the specified effective 
date of such Corporate Transaction, for all of the Shares at the time
represented by such Award and may be exercised with respect to any or all of 
such Shares represented by such Award.  Effective upon the consummation of the
Corporate Transaction, all outstanding Awards under the Plan shall terminate 
unless assumed by the successor company or its Parent.
    

          (b)  Should a Change in Control (other than a Change in Control which
is also a Corporate Transaction) occur while an Grantee's Continuous Status as
an Employee, Director or Consultant has not terminated, then each outstanding
Award held by such Grantee, unless otherwise determined by the Administrator,
shall become fully vested and exercisable and be released from any restrictions
on transfer and repurchase or forfeiture rights, immediately prior to the
specified effective date of such Change in Control, for all of the Shares at the
time subject to such Award and may be exercised with respect to any or all of
such Shares represented by such Award.  Each such Award shall remain so
exercisable until the expiration or sooner termination of the applicable Award
term.

          (c)  Should a Subsidiary Disposition occur while an Grantee's
Continuous Status as an Employee, Director or Consultant with the subsidiary
corporation involved in such Subsidiary Disposition has not terminated, then
each outstanding Award held by such Grantee, unless otherwise determined by the
Administrator, shall become fully vested and exercisable and be released from
any restrictions on transfer and repurchase or forfeiture rights, immediately
prior to the specified effective date of such Subsidiary Disposition, for all of
the Shares at the time subject to such Award and may be exercised with respect
to any or all of such Shares represented by such Award.  Each such Award shall
remain so exercisable until the expiration or sooner termination of the Award
term.

          (d)  The portion of any Incentive Stock Option accelerated under this
Section 11 in connection with a Corporate Transaction, Change in Control or
Subsidiary Disposition shall remain exercisable as an Incentive Stock Option
under the Code only to the extent the $100,000 dollar limitation of
Section 422(d) of the Code is not exceeded.  To the extent such dollar
limitation is exceeded, the accelerated excess portion of such Option shall be
exercisable as a Non-Qualified Stock Option.


                                       11
<PAGE>


     12.  TERM OF PLAN.  The Plan shall become effective upon the earlier to
occur of its adoption by the Board or its approval by the shareholders of the
Company.  It shall continue in effect for a term of ten (10) years unless sooner
terminated.

     13.  AMENDMENT, SUSPENSION OR TERMINATION OF THE PLAN.

          (a)  The Board may at any time amend, suspend or terminate the Plan.
To the extent necessary and desirable to comply with Applicable Laws, the
Company shall obtain shareholder approval of any Plan amendment in such a manner
and to such a degree as required.

          (b)  No Award may be granted during any suspension or after
termination of the Plan.

          (c)  Any amendment, suspension or termination of the Plan shall not
affect Awards already granted, and such Awards shall remain in full force and
effect as if the Plan had not been amended, suspended or terminated, unless
mutually agreed otherwise between the Grantee and the Administrator, which
agreement must be in writing and signed by the Grantee and the Company.

     14.  RESERVATION OF SHARES.

          (a)  The Company, during the term of the Plan, will at all times
reserve and keep available such number of Shares as shall be sufficient to
satisfy the requirements of the Plan.

          (b)  The inability of the Company to obtain authority from any
regulatory body having jurisdiction, which authority is deemed by the Company's
counsel to be necessary to the lawful issuance and sale of any Shares hereunder,
shall relieve the Company of any liability in respect of the failure to issue or
sell such Shares as to which such requisite authority shall not have been
obtained.

     15.  NO EFFECT ON TERMS OF EMPLOYMENT.  The Plan shall not confer upon any
Grantee any right with respect to continuation of employment or consulting
relationship with the Company, nor shall it interfere in any way with his or her
right or the Company's right to terminate his or her employment or consulting
relationship at any time, with or without cause.

     16.  SHAREHOLDER APPROVAL.  Continuance of the Plan with respect to the
grant of Incentive Stock Options shall be subject to approval by the
shareholders of the Company within twelve (12) months before or after the date
the Plan is adopted.  Such shareholder approval shall be obtained in the degree
and manner required under Applicable Laws.


                                       12
<PAGE>


                      PROGENITOR, INC. 1996 STOCK INCENTIVE PLAN

                                STOCK OPTION AGREEMENT

I.     NOTICE OF STOCK OPTION GRANT

       Optionee's Name and Address:
                                       -----------------------------------

                                       -----------------------------------

                                       -----------------------------------

       You have been granted an option to purchase shares of Common Stock of
the Company, subject to the terms and conditions of the Plan and this Option
Agreement, as follows:

       Grant Number
                                       -----------------------------------
       Date of Grant
                                       -----------------------------------
       Vesting Commencement Date
                                       -----------------------------------
       Exercise Price per Share        $
                                        ----------------------------------
       Total Number of Shares Granted
                                       -----------------------------------
       Total Exercise Price            $
                                       -----------------------------------
       Type of Option:                           Incentive Stock Option
                                       ------
                                                 Non-Qualified Stock Option
                                       ------
       Term/Expiration Date:
                                       -----------------------------------

VESTING SCHEDULE:

       Subject to other limitations set forth in this Agreement, this Option
may be exercised, in whole or in part, in accordance with the following
schedule:

   
    

TERMINATION PERIOD:

   
       This Option may be exercised for THREE (3) months after termination of
the Optionee's employment or consulting relationship, or such longer period as
may be applicable upon death or disability of Optionee as provided in the
Agreement.  In the event of the Optionee's change in status from Employee to
Consultant or Consultant to Employee, this Option Agreement shall remain in
effect; provided, however, that in the event of a change in status from Employee
to Consultant, Optionee's Incentive Stock Option shall cease to be treated as an
Incentive Stock Option and shall be treated as a Non-Qualified Stock Option on
the ninety-first (91st) day
    

                                          1

<PAGE>

following such change in status.  In no event shall this Option be exercised
later than the Term/Expiration Date as provided above.


                                          2

<PAGE>

II.    AGREEMENT

       1.      GRANT OF OPTION.  Progenitor, Inc., a Delaware corporation (the
"Company"), hereby grants to the Optionee named in the Notice of Stock Option
Grant (the "Optionee"), an option (the "Option") to purchase the total number of
shares of Common Stock (the "Shares") set forth in the Notice of Stock Option
Grant, at the exercise price per share set forth in the Notice of Stock Option
Grant (the "Exercise Price") subject to the terms, definitions and provisions of
the Company's 1996 Stock Incentive Plan (the "Plan") adopted by the Company,
which is incorporated herein by reference.  Unless otherwise defined herein, the
terms defined in the Plan shall have the same defined meanings in this Option
Agreement.

       If designated in the Notice of Stock Option Grant as an Incentive Stock
Option, this Option is intended to qualify as an Incentive Stock Option as
defined in Section 422 of the Code.  Nevertheless, to the extent that it exceeds
the $100,000 rule of Section 422(d) of the Code, this Option shall be treated as
a Non-Qualified Stock Option.

       2.      EXERCISE OF OPTION.

               (a)     RIGHT TO EXERCISE.  This Option shall be exercisable
during its term in accordance with the Vesting Schedule set out in the Notice of
Stock Option Grant and with the applicable provisions of the Plan and this
Option Agreement.  In the event of termination of Optionee's Continuous Status
as an Employee, Director or Consultant, this Option shall be exercisable in
accordance with the applicable provisions of the Plan and this Option Agreement.
This Option shall be subject to the provisions of Section 11 of the Plan
relating to the exercisability or termination of the Option in the event of a
Corporate Transaction, Change in Control or Subsidiary Disposition.

               (b)     METHOD OF EXERCISE.  This Option shall be exercisable
only by delivery of an Exercise Notice (attached as Exhibit A) which shall state
the election to exercise the Option, the whole number of Shares in respect of
which the Option is being exercised, such other representations and agreements
as to the holder's investment intent with respect to such Shares and such other
provisions as may be required by the Administrator.  Such Exercise Notice shall
be signed by the Optionee and shall be delivered in person or by certified mail
to the Secretary of the Company accompanied by payment of the Exercise Price.
The Option shall be deemed to be exercised upon receipt by the Company of such
written notice accompanied by the Exercise Price.

               No Shares will be issued pursuant to the exercise of the Option
unless such issuance and such exercise shall comply with all Applicable Laws.
Assuming such compliance, for income tax purposes, the Shares shall be
considered transferred to the Optionee on the date on which the Option is
exercised with respect to such Shares.

               (c)     TAXES.  No Shares will be issued to the Optionee or
other person pursuant to the exercise of the Option until the Optionee or other
person has made arrangements


                                          3

<PAGE>

acceptable to the Administrator for the satisfaction of foreign, federal, state
and local income and employment tax withholding obligations.

       3.      METHOD OF PAYMENT.  Payment of the Exercise Price shall be by
any of the following, or a combination thereof, at the election of the Optionee;
provided, however, that such exercise method does not then violate an Applicable
Law:

               (a)     cash;

               (b)     check;

               (c)     [SURRENDER OF SHARES OF COMMON STOCK OF THE COMPANY
(INCLUDING WITHHOLDING OF SHARES OTHERWISE DELIVERABLE UPON EXERCISE OF THIS
OPTION) WHICH HAVE A FAIR MARKET VALUE ON THE DATE OF SURRENDER EQUAL TO THE
EXERCISE PRICE OF THE SHARES AS TO WHICH THE OPTION IS BEING EXERCISED (BUT ONLY
TO THE EXTENT THAT SUCH EXERCISE OF THE OPTION WOULD NOT RESULT IN AN ACCOUNTING
COMPENSATION CHARGE WITH RESPECT TO THE SHARES USED TO PAY THE EXERCISE PRICE
UNLESS OTHERWISE DETERMINED BY THE ADMINISTRATOR); OR

               (d)     DELIVERY OF A PROPERLY EXECUTED EXERCISE NOTICE TOGETHER
WITH SUCH OTHER DOCUMENTATION AS THE ADMINISTRATOR AND THE BROKER, IF
APPLICABLE, SHALL REQUIRE TO EFFECT AN EXERCISE OF THE OPTION AND DELIVERY TO
THE COMPANY OF THE SALE OR LOAN PROCEEDS REQUIRED TO PAY THE EXERCISE PRICE].

       [ADD ANY ADDITIONAL EXERCISE METHODS, SUCH AS RECOURSE LOAN]

       4.      RESTRICTIONS ON EXERCISE.  This Option, if an Incentive Stock
Option, may not be exercised until such time as the Plan has been approved by
the stockholders of the Company.  In addition, this Option may not be exercised
if the issuance of the Shares subject to the Option upon such exercise would
constitute a violation of any Applicable Laws.

       5.      TERMINATION OF RELATIONSHIP.  In the event the Optionee's
Continuous Status as an Employee, Director or Consultant terminates, the
Optionee may, to the extent otherwise so entitled at the date of such
termination (the "Termination Date"), exercise this Option during the
Termination Period set out in the Notice of Stock Option Grant.  Except as
provided in Sections 6 and 7, below, to the extent that the Optionee was not
entitled to exercise this Option on the Termination Date, or if the Optionee
does not exercise this Option within the Termination Period, the Option shall
terminate.

       6.      DISABILITY OF OPTIONEE.  In  the Optionee's Continuous Status as
an Employee, Director or Consultant terminates as a result of his or her
disability, the Optionee may, but only within twelve (12) months from the
Termination Date (and in no event later than the Term/Expiration Date), exercise
the Option to the extent otherwise entitled to exercise it on the Termination
Date; provided, however, that if such disability is not a "disability" as such
term is defined in Section 22(e)(3) of the Code and the Option is an Incentive
Stock Option, such Incentive Stock Option shall cease to be treated as an
Incentive Stock Option and shall be treated as a Non-Qualified Stock Option on
the ninety-first (91st) day following the Termination Date.  To the extent that
the Optionee was not entitled to exercise the Option on the Termination Date,


                                          4

<PAGE>

or if the Optionee does not exercise such Option to the extent so entitled
within the time specified herein, the Option shall terminate.

       7.      DEATH OF OPTIONEE.  In the event of the Optionee's death, the
Option may be exercised at any time within twelve (12) months following the date
of death (and in no event later than the Term/Expiration Date), by the
Optionee's estate or by a person who acquired the right to exercise the Option
by bequest or inheritance, but only to the extent the Optionee could exercise
the Option at the date of death.

       8.      TRANSFERABILITY OF OPTION.  This Option, if an Incentive Stock
Option, may not be transferred in any manner otherwise than by will or by the
laws of descent or distribution and may be exercised during the lifetime of the
Optionee only by the Optionee.  This Option, if a Non-Qualified Stock Option,
may be transferred by the Optionee in a manner and to the extent acceptable to
the Administrator as evidenced by a writing signed by the Company and the
Optionee.  The terms of this Option shall be binding upon the executors,
administrators, heirs and successors of the Optionee.

       9.      TERM OF OPTION.  This Option may be exercised only within the
term set out in the Notice of Stock Option Grant, and may be exercised during
such term only in accordance with the Plan and the terms of this Option
Agreement.

   
       10.     TAX CONSEQUENCES.  Set forth below is a brief summary as of the
date of this Option Agreement of some of the federal tax consequences of 
exercise of this Option and disposition of the Shares.  THIS SUMMARY IS 
NECESSARILY INCOMPLETE, AND THE TAX LAWS AND REGULATIONS ARE SUBJECT TO 
CHANGE.  OPTIONEE SHOULD CONSULT A TAX ADVISER BEFORE EXERCISING THIS OPTION 
OR DISPOSING OF THE SHARES.
    

   
               (a)     EXERCISE OF INCENTIVE STOCK OPTION.  If this Option
qualifies as an Incentive Stock Option, there will be no regular federal income
tax liability upon the exercise of the Option, although the excess, if any, 
of the Fair Market Value of the Shares on the date of exercise over the 
Exercise Price will be treated as an adjustment to the alternative minimum 
tax for federal tax purposes and may subject the Optionee to the alternative 
minimum tax in the year of exercise.
    

               (b)     EXERCISE OF INCENTIVE STOCK OPTION FOLLOWING DISABILITY.
If the Optionee's Continuous Status as an Employee, Director or Consultant
terminates as a result of disability that is not total and permanent disability
as defined in Section 22(e)(3) of the Code, to the extent permitted on the date
of termination, the Optionee must exercise an Incentive Stock Option within 90
days of such termination for the Incentive Stock Option to be qualified as an
Incentive Stock Option.

   
               (c)     EXERCISE OF NON-QUALIFIED STOCK OPTION.  There may be a
regular federal income tax liability upon the exercise of a Non-Qualified 
Stock Option.  The Optionee will be treated as having received compensation 
income (taxable at ordinary income tax rates) equal to the excess, if any, of 
the Fair Market Value of the Shares on
    

                                          5

<PAGE>

the date of exercise over the Exercise Price.  If Optionee is an Employee or a
former Employee, the Company will be required to withhold from Optionee's
compensation or collect from Optionee and pay to the applicable taxing
authorities an amount in cash equal to a percentage of this compensation income
at the time of exercise, and may refuse to honor the exercise and refuse to
deliver Shares if such withholding amounts are not delivered at the time of
exercise.

   
               (d)     DISPOSITION OF SHARES.  In the case of a Non-Qualified
Stock Option, if Shares are held for at least one year, any gain realized on
disposition of the Shares will be treated as long-term capital gain for federal
income tax purposes.  In the case of an Incentive Stock Option, if Shares 
transferred pursuant to the Option are held for at least one year after 
receipt of the Shares and are disposed of at least two years after the Date 
of Grant, any gain realized on disposition of the Shares also will be treated 
as long-term capital gain for federal income tax purposes.  If Shares 
purchased under an Incentive Stock Option are disposed of within such 
one-year or two-year periods, any gain realized on such disposition will be 
treated as compensation income (taxable at ordinary income rates) to the 
extent of the difference between the Exercise Price and the lesser of (i) the 
Fair Market Value of the Shares on the date of exercise, or (ii) the sale 
price of the Shares.
    

   
       11.     ENTIRE AGREEMENT: GOVERNING LAW.  The Plan is incorporated
herein by reference.  The Plan and this Option Agreement constitute the entire
agreement of the parties with respect to the subject matter hereof and supersede
in their entirety all prior undertakings and agreements of the Company and the
Optionee with respect to the subject matter hereof, and may not be modified
adversely to the Optionee's interest except by means of a writing signed by the
Company and Optionee.  This agreement is governed by Delaware law except for
that body of law pertaining to conflict of laws.
    

       12.     HEADINGS.  The captions used in this Option are inserted for
convenience and shall not be deemed a part of this Option for construction or
interpretation.


                                          6

<PAGE>

       13.     INTERPRETATION.  Any dispute regarding the interpretation of
this Option Agreement shall be submitted by the Optionee or by the Company
forthwith to the Board or the Administrator that administers the Plan, which
shall review such dispute at its next regular meeting.  The resolution of such
dispute by the Board or the Administrator shall be final and binding on all
persons.

                                       Progenitor, Inc.,
                                       a Delaware corporation
                                       By:
                                          -----------------------------------

                                       Its:
                                           ----------------------------------

OPTIONEE ACKNOWLEDGES AND AGREES THAT THE VESTING OF SHARES PURSUANT TO THE
OPTION HEREOF IS EARNED ONLY BY CONTINUING CONSULTANCY OR EMPLOYMENT AT THE WILL
OF THE COMPANY (NOT THROUGH THE ACT OF BEING HIRED, BEING GRANTED THIS OPTION OR
ACQUIRING SHARES HEREUNDER).  OPTIONEE FURTHER ACKNOWLEDGES AND AGREES THAT
NOTHING IN THIS AGREEMENT, NOR IN THE COMPANY'S 1996 STOCK INCENTIVE PLAN WHICH
IS INCORPORATED HEREIN BY REFERENCE, SHALL CONFER UPON OPTIONEE ANY RIGHT WITH
RESPECT TO CONTINUATION OF EMPLOYMENT OR CONSULTANCY BY THE COMPANY, NOR SHALL
IT INTERFERE IN ANY WAY WITH OPTIONEE'S RIGHT OR THE COMPANY'S RIGHT TO
TERMINATE OPTIONEE'S EMPLOYMENT OR CONSULTANCY AT ANY TIME, WITH OR WITHOUT
CAUSE.

       Optionee acknowledges receipt of a copy of the Plan and represents that
he is familiar with the terms and provisions thereof, and hereby accepts this
Option Agreement subject to all of the terms and provisions thereof.  Optionee
has reviewed the Plan and this Option Agreement in their entirety, has had an
opportunity to obtain the advice of counsel prior to executing this Option
Agreement and fully understands all provisions of the Option Agreement.
Optionee hereby agrees to accept as binding, conclusive and final all decisions
or interpretations of the Administrator upon any questions arising under the
Plan or this Option Agreement.  Optionee further agrees to notify the Company
upon any change in the residence address indicated below.

Dated:                                 Signed:
      -----------------------------           -------------------------------
                                              Optionee

                                       Residence Address:

                                       --------------------------------------

                                       --------------------------------------

                                       --------------------------------------


                                          7

<PAGE>

                                      EXHIBIT A

                      PROGENITOR, INC. 1996 STOCK INCENTIVE PLAN

                                   EXERCISE NOTICE


Progenitor, Inc.
1507 Chambers Road
Columbus, OH  43212

Attention: Secretary

      1.     EXERCISE OF OPTION.  Effective as of today, ______________,
________________________________, the undersigned ("Optionee") hereby elects to
exercise Optionee's option to purchase ___________ shares of the Common Stock
(the "Shares") of Progenitor, Inc. (the "Company") under and pursuant to the
Company's 1996 Stock Incentive Plan (the "Plan") and the [  ] Incentive
[  ] Non-Qualified Stock Option Agreement dated ______________, ________ (the
"Option Agreement").

      2.     REPRESENTATIONS OF OPTIONEE.  Optionee acknowledges that Optionee
has received, read and understood the Plan and the Option Agreement and agrees
to abide by and be bound by their terms and conditions.

      3.     RIGHTS AS STOCKHOLDER.  Until the stock certificate evidencing
such Shares is issued (as evidenced by the appropriate entry on the books of the
Company or of a duly authorized transfer agent of the Company), no right to vote
or receive dividends or any other rights as a stockholder shall exist with
respect to the Optioned Stock, notwithstanding the exercise of the Option.  The
Company shall issue (or cause to be issued) such stock certificate promptly
after the Option is exercised.  No adjustment will be made for a dividend or
other right for which the record date is prior to the date the stock certificate
is issued, except as provided in Section 10 of the Plan.

      4.     DELIVERY OF PAYMENT.  Optionee herewith delivers to the Company
the full Exercise Price for the Shares.

      5.     TAX CONSULTATION.  Optionee understands that Optionee may suffer
adverse tax consequences as a result of Optionee's purchase or disposition of
the Shares.  Optionee represents that Optionee has consulted with any tax
consultants Optionee deems advisable in connection with the purchase or
disposition of the Shares and that Optionee is not relying on the Company for
any tax advice

      6.     TAXES.  Optionee agrees to satisfy all applicable federal, state
and local income and employment tax withholding obligations and [HEREWITH
DELIVERS TO THE COMPANY THE FULL AMOUNT OF SUCH OBLIGATIONS] OR [HAS MADE
ARRANGEMENTS ACCEPTABLE TO THE COMPANY TO SATISFY SUCH OBLIGATIONS.]  [OPTIONEE
ALSO AGREES, AS PARTIAL CONSIDERATION FOR THE DESIGNATION


                                          1

<PAGE>

OF THE OPTION AS AN INCENTIVE STOCK OPTION, TO NOTIFY THE COMPANY IN WRITING
WITHIN THIRTY (30) DAYS OF ANY DISPOSITION OF ANY SHARES ACQUIRED BY EXERCISE OF
THE OPTION IF SUCH DISPOSITION OCCURS WITHIN TWO (2) YEARS FROM THE GRANT DATE
OR WITHIN ONE (1) YEAR FROM THE DATE THE SHARES WERE TRANSFERRED TO OPTIONEE.
IF THE COMPANY IS REQUIRED TO SATISFY ANY FEDERAL, STATE OR LOCAL INCOME OR
EMPLOYMENT TAX WITHHOLDING OBLIGATIONS AS A RESULT OF SUCH AN EARLY DISPOSITION,
OPTIONEE AGREES TO SATISFY THE AMOUNT OF SUCH WITHHOLDING IN A MANNER THAT THE
ADMINISTRATOR PRESCRIBES.]

      7.     SUCCESSORS AND ASSIGNS.  The Company may assign any of its rights
under this Exercise Notice to single or multiple assignees, and this Agreement
shall inure to the benefit of the successors and assigns of the Company.  This
Exercise Notice shall be binding upon Optionee and his or her heirs, executors,
administrators, successors and assigns.

      8.     HEADINGS.  The captions used in this Agreement are inserted for
convenience and shall not be deemed a part of this Agreement for construction or
interpretation.

      9.     INTERPRETATION.  Any dispute regarding the interpretation of this
Exercise Notice shall be submitted by Optionee or by the Company forthwith to
the Company's Board of Directors or the Administrator that administers the Plan,
which shall review such dispute at its next regular meeting.  The resolution of
such a dispute by the Board or Administrator shall be final and binding on all
persons.

   
      10.    GOVERNING LAW; SEVERABILITY.  This Agreement shall be governed by
and construed in accordance with the laws of the State of Delaware excluding
that body of law pertaining to conflicts of law.  Should any provision of this
Agreement be determined by a court of law to be illegal or unenforceable, the
other provisions shall nevertheless remain effective and shall remain
enforceable.
    

      11.    NOTICES.  Any notice required or permitted hereunder shall be
given in writing and shall be deemed effectively given upon personal delivery or
upon deposit in the United States mail by certified mail, with postage and fees
prepaid, addressed to the other party at its address as shown below beneath its
signature, or to such other address as such party may designate in writing from
time to time to the other party.

      12.    FURTHER INSTRUMENTS.  The parties agree to execute such further
instruments and to take such further action as may be reasonably necessary to
carry out the purposes and intent of this Agreement.


                                          2

<PAGE>

      13.    ENTIRE AGREEMENT.  The Plan and the Option Agreement are
incorporated herein by reference.  This Exercise Notice, the Plan and the Option
Agreement constitute the entire agreement of the parties with respect to the
subject matter hereof and supersede in their entirety all prior undertakings and
agreements of the Company and Optionee with respect to the subject matter
hereof, and may not be modified adversely to the Optionee's interest except by
means of a writing signed by the Company and Optionee.

Submitted by:                          Accepted by:

OPTIONEE:                              PROGENITOR, INC.
                                       By:
                                          -----------------------------------

- -----------------------------------    Its:
(Signature)                                ----------------------------------


ADDRESS:                               ADDRESS:

___________________________________    1507 Chambers Road
___________________________________    Columbus, OH  43212


                                          3

<PAGE>

                                                                    Exhibit 23.1


                          CONSENT OF INDEPENDENT ACCOUNTANTS

We consent to the inclusion in this registration statement on Form S-1 (File No.
333-05369) of our report, which includes an explanatory paragraph regarding the
Company's ability to continue as a going concern, dated June 5, 1996 on our
audits of the financial statements of Progenitor, Inc. (a Development Stage
Company).  We also consent to the reference to our firm under the caption
"Experts."

                                       COOPERS & LYBRAND L.L.P.

Columbus, Ohio
July 10, 1996


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