CN BIOSCIENCES INC
10-Q, 1998-11-13
MEDICINAL CHEMICALS & BOTANICAL PRODUCTS
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<PAGE>   1
                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM 10-Q

(Mark One)
    [X]     QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
            EXCHANGE ACT OF 1934

            FOR THE QUARTERLY PERIOD ENDED SEPTEMBER 30, 1998
            
                                       OR

    [ ]    TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
           SECURITIES EXCHANGE ACT OF 1934

           FOR THE TRANSITION PERIOD FROM _____ TO _____

                        COMMISSION FILE NUMBER 000-21281


                              CN BIOSCIENCES, INC.
             (Exact name of registrant as specified in its charter)


          DELAWARE                                           33-0509785
- -------------------------------                           -------------------
(State or other jurisdiction of                            (I.R.S. Employer
 incorporation or organization)                           Identification No.)

10394 PACIFIC CENTER COURT, SAN DIEGO, CA                       92121
- -----------------------------------------                     ----------
 (Address of principal executive offices)                     (Zip Code)

Registrant's telephone number, including area code:         (619) 450-5500
                                                            --------------

                                       N/A
              (Former name, former address and former fiscal year,
                         if changed since last report)

Indicate by check mark whether the registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the preceding 12 months (or for such shorter period that the registrant was
required to file such reports), and (2) has been subject to such filing
requirements for the past 90 days. Yes (X) No ( )

Indicate the number of shares of each of the issuer's classes of common stock,
as of the latest practicable date:

          Class                                          November 6, 1998
- ----------------------------                             ----------------
Common Stock, $.01 Par Value                                 5,721,790




<PAGE>   2

                              CN BIOSCIENCES, INC.
                               INDEX TO FORM 10-Q


<TABLE>
<CAPTION>
PART I.  FINANCIAL INFORMATION

Item 1. Financial Statements
<S>     <C>                                                                          <C>
        Condensed Consolidated Balance Sheets as of September 30, 1998
        (unaudited) and December 31, 1997                                             3

        Condensed Consolidated Statements of Income for the Three Months
        and Nine Months Ended September 30, 1998 and 1997 (unaudited)                 4

        Condensed Consolidated Statements of Cash Flows for the Nine Months
        Ended September 30, 1998 and 1997 (unaudited)                                 5

        Notes to Interim Condensed Consolidated Financial Statements (unaudited)      6

Item 2. Management's Discussion and Analysis of Financial Condition
        and Results of Operations                                                     7

Item 3. Quantitative and Qualitative Disclosures About Market Risk                   16


PART II.  OTHER INFORMATION

Item 6. Exhibits and Reports on Form 8-K                                             17

SIGNATURES

INDEX OF EXHIBITS
</TABLE>



                                       2
<PAGE>   3

PART I.  FINANCIAL INFORMATION

Item 1.  Financial Statements

                              CN BIOSCIENCES, INC.
                      CONDENSED CONSOLIDATED BALANCE SHEETS


<TABLE>
<CAPTION>
                                                  SEPTEMBER 30, 1998   DECEMBER 31, 1997
                                                  ------------------   -----------------
                                                     (UNAUDITED)             (Note)
                                                     -----------             ------
<S>                                                   <C>                 <C>
ASSETS

    Current assets:
        Cash, cash equivalents and short-term         $  7,314,000        $ 17,692,000
            investments
        Accounts receivable, net                         6,649,000           5,914,000
        Inventories                                     21,976,000          18,309,000
        Other current assets                             2,958,000           2,800,000
                                                      ------------        ------------
    Total current assets                                38,897,000          44,715,000

    Property and equipment, net                          5,040,000           4,528,000
    Intangible assets, net                               9,462,000          10,330,000
    Other assets                                         1,717,000             838,000
                                                      ------------        ------------
    Total assets                                      $ 55,116,000        $ 60,411,000
                                                      ============        ============

LIABILITIES AND STOCKHOLDERS' EQUITY

    Current liabilities:
      Accounts payable, trade                         $  2,176,000        $  2,505,000
      Liability for purchase of business                        --          10,500,000
      Accrued expenses                                   2,854,000           3,898,000
      Other current liabilities                          1,994,000             837,000
                                                      ------------        ------------
    Total current liabilities                            7,024,000          17,740,000

    Other liabilities                                    3,376,000           3,565,000

    Stockholders' equity:
      Common stock                                          57,000              56,000
      Additional paid-in capital                        43,641,000          42,481,000
      Accumulated earnings (deficit)                       767,000          (3,043,000)
      Foreign currency translation adjustment              251,000            (388,000)
                                                      ------------        ------------
    Total stockholders' equity                          44,716,000          39,106,000
                                                      ------------        ------------
    Total liabilities and stockholders' equity        $ 55,116,000        $ 60,411,000
                                                      ============        ============
</TABLE>


See accompanying notes.


Note:   The balance sheet at December 31, 1997 has been derived from the audited
        consolidated financial statements at that date, but does not include all
        of the disclosures required by generally accepted accounting principles.



                                       3
<PAGE>   4

                              CN BIOSCIENCES, INC.
                   CONDENSED CONSOLIDATED STATEMENTS OF INCOME
                                   (UNAUDITED)


<TABLE>
<CAPTION>
                             THREE MONTHS ENDED SEPTEMBER 30,   NINE MONTHS ENDED SEPTEMBER 30,
                             --------------------------------   -------------------------------
                                   1998             1997             1998             1997
                               -----------      -----------      -----------      -----------
<S>                            <C>              <C>              <C>              <C>
Sales                          $12,634,000      $ 9,630,000      $38,180,000      $29,421,000
Cost of sales                    5,651,000        4,319,000       17,148,000       13,209,000
                               -----------      -----------      -----------      -----------
Gross profit                     6,983,000        5,311,000       21,032,000       16,212,000
Operating expenses:
  Selling, general and
     administrative              4,190,000        3,399,000       12,616,000       10,448,000
  Research and development         832,000          650,000        2,525,000        1,886,000
                               -----------      -----------      -----------      -----------
Total operating expenses         5,022,000        4,049,000       15,141,000       12,334,000
                               -----------      -----------      -----------      -----------
Income from operations           1,961,000        1,262,000        5,891,000        3,878,000
Interest income, net                47,000          176,000          125,000          420,000
                               -----------      -----------      -----------      -----------
Income before income taxes       2,008,000        1,438,000        6,016,000        4,298,000
Provision for income taxes         736,000          474,000        2,206,000        1,462,000
                               -----------      -----------      -----------      -----------
     Net income                $ 1,272,000      $   964,000      $ 3,810,000      $ 2,836,000
                               ===========      ===========      ===========      ===========
Net income per share
     Basic                     $       .22      $       .17      $       .67      $       .53
                               ===========      ===========      ===========      ===========
     Diluted                   $       .22      $       .17      $       .65      $       .50
                               ===========      ===========      ===========      ===========
Shares used in per share
  Computations
     Basic                       5,697,000        5,562,000        5,673,000        5,383,000
                               ===========      ===========      ===========      ===========
     Diluted                     5,901,000        5,828,000        5,883,000        5,693,000
                               ===========      ===========      ===========      ===========
</TABLE>











See accompanying notes.



                                       4
<PAGE>   5

                              CN BIOSCIENCES, INC.
                 CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
                                   (UNAUDITED)


<TABLE>
<CAPTION>
                                                      NINE MONTHS ENDED SEPTEMBER 30,
                                                    ---------------------------------
                                                        1998                 1997
                                                    ------------         ------------
<S>                                                 <C>                  <C>
OPERATING ACTIVITIES
Net income                                          $  3,810,000         $  2,836,000
Adjustments to reconcile net income to net
    cash used in operations:
  Depreciation and amortization                        2,242,000            1,809,000
  Additions to inventory reserve                         440,000              285,000
  Loss on disposal of property and equipment                  --                5,000
  Changes in assets and liabilities:
     Accounts receivable, trade                         (398,000)          (1,474,000)
     Inventories                                      (3,770,000)          (2,520,000)
     Other current assets                               (118,000)             359,000
     Other assets                                     (1,340,000)            (832,000)
     Accounts payable, trade                            (479,000)             474,000
     Accrued expenses                                 (1,063,000)             515,000
     Other current liabilities                         1,081,000             (704,000)
     Other liabilities                                  (160,000)            (220,000)
                                                    ------------         ------------
Net cash provided by operating activities                245,000              533,000


INVESTING ACTIVITIES
Purchases of property and equipment                   (1,374,000)          (1,238,000)
Purchase of business                                 (10,500,000)                  --
Other                                                    (29,000)                  --
                                                    ------------         ------------
Net cash used in investing activities                (11,903,000)          (1,238,000)

FINANCING ACTIVITIES
Proceeds from the sale of common stock                 1,206,000            3,562,000
                                                    ------------         ------------
Net cash provided by financing activities              1,206,000            3,562,000

Effect of exchange rate changes on cash
                                                          74,000             (145,000)
                                                    ------------         ------------
Net increase (decrease) in cash and cash             (10,378,000)           2,712,000
equivalents

Balance at beginning of period                        17,692,000           14,704,000
                                                    ------------         ------------
Balance at end of period                            $  7,314,000         $ 17,416,000
                                                    ============         ============
Supplemental cash flow information:
  Interest paid during the period                   $     48,000         $     99,000
                                                    ============         ============
  Income taxes paid during the period               $    268,000         $  1,080,000
                                                    ============         ============
</TABLE>



See accompanying notes.



                                       5
<PAGE>   6

                              CN BIOSCIENCES, INC.
          NOTES TO INTERIM CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
                                   (UNAUDITED)


     1.   BASIS OF PRESENTATION

     The interim unaudited condensed consolidated financial statements of CN
Biosciences, Inc. (the "Company") contained herein have been prepared in
accordance with generally accepted accounting principles for interim financial
information. Accordingly, they do not include all of the information and
footnotes required by generally accepted accounting principles for complete
financial statements. These consolidated financial statements should be read in
conjunction with the consolidated financial statements and notes thereto for the
year ended December 31, 1997 included in the Company's Annual Report on Form
10-K filed with the Securities and Exchange Commission. In management's opinion,
the unaudited information includes all adjustments (consisting only of normal
recurring adjustments) necessary for a fair presentation of the financial
position, results of operations and cash flows for the periods presented.
Interim results are not necessarily indicative of results to be expected for the
full year.

     2.   NEW ACCOUNTING STANDARDS

     Effective January 1, 1998, the Company adopted the Financial Accounting
Standards Board's Statement No. 130, Comprehensive Income, ("SFAS 130"), and
Statement No. 131, Disclosures about Segments of an Enterprise and Related
Information ("SFAS 131"). SFAS 130 establishes new rules for the reporting and
display of comprehensive income and its components, however, the adoption of
SFAS 130 had no impact on the Company's net income or stockholder's equity. SFAS
130 requires the change in the foreign currency translation adjustment be
included in comprehensive income. As adjusted for this item, comprehensive
income is $4,213,000 and $2,442,000 for the nine-month periods ended September
30, 1998 and 1997, and $1,923,000 and $983,000 for the three-month periods ended
September 30, 1998 and 1997. SFAS 131 establishes standards for the way that
public business enterprises report information about operating segments in
annual financial statements and requires that those enterprises report selected
information about operating segments in interim financial reports. SFAS 131 also
establishes standards for related disclosures about products and services,
geographic areas and major customers. The adoption of SFAS 131 did not affect
results of operations or financial position, and did not affect the disclosure
of segment information because SFAS 131 is not required to be applied to interim
financial statements in the initial year of adoption.

     3.   INVENTORIES

     Inventories consist of the following:

<TABLE>
<CAPTION>
                                               September 30, 1998   December 31, 1997
                                               ------------------   -----------------
<S>                                            <C>                  <C>
     Finished products                             $17,466,000         $15,542,000
     Semi-finished products, raw materials
       and supplies                                  7,965,000           6,056,000
     Work-in-progress                                  663,000             517,000
                                                   -----------         -----------
                                                    26,094,000          22,115,000
     Reserves for excess materials                  (4,118,000)         (3,806,000)
                                                   -----------         -----------
          Total                                    $21,976,000         $18,309,000
                                                   ===========         ===========
</TABLE>


     Inventories are maintained to support customer deliveries worldwide, often
on a next-day or second-day basis, of many sizes and quantities of each brand of
catalog items. Based upon economic production runs for certain products, the
Company from time to time manufactures quantities of product in excess of a
one-year supply. Inventories are valued at the lower of cost (first-in,
first-out basis) or market, with costs including material, labor and
manufacturing overhead.




                                       6
<PAGE>   7

Item 2.

                     MANAGEMENT'S DISCUSSION AND ANALYSIS OF
                  FINANCIAL CONDITION AND RESULTS OF OPERATIONS


     OVERVIEW

     The Company was formed in 1992 with the purchase of the Company's
subsidiaries, including the Calbiochem biochemical and immunochemical operations
headquartered in San Diego, California, and the Novabiochem peptide operations
headquartered in Laufelfingen, Switzerland, from Biodor Holding AG, Ixora
Holding AG and Biodor US Holding Corporation.

     In August 1995, the Company expanded its immunochemical and molecular
biology capabilities with the purchase of the Oncogene Research Products
business from Oncogene Science, Inc. (now known as OSI Pharmaceuticals, Inc.,
"OSI") for $6.2 million cash, which was funded by bank debt. The acquisition and
successful integration of this business enhanced the depth and breadth of the
Company's scientific resources, while providing a complementary base of products
and customers.

     In December 1997, the Company expanded its molecular biology capabilities
with the purchase of all of the outstanding capital stock of Novagen, Inc.
("Novagen"), a privately owned company, together with all of the outstanding
capital stock of its parent holding company, for a purchase price of $10.5
million cash. Assets acquired included receivables and inventory, and intangible
assets including in-process technology valued at $6.8 million, which was written
off effective as of the purchase date. The acquisition of this business further
broadened the Company's product line and added an important brand identity in
molecular biology.

     The Company uses general and specialty catalogs to market a broad range of
brand-name research products to life sciences researchers worldwide at
pharmaceutical and biotechnology companies, academic institutions and government
laboratories. The Company invests significantly in producing each of its
catalogs, and associated costs are capitalized and amortized over the estimated
useful life of the catalog, generally 12 to 24 months.

     Since 1993, the Company has increasingly focused its strategy on its higher
margin core business of providing standard laboratory quantity sizes of products
(generally ranging from 100 nanograms to 100 grams), and has reduced the focus
on its bulk business. Bulk quantities (generally up to ten kilograms) are
generally offered at discounts to catalog prices, and bulk sales are
characterized as relatively high dollar sales made to a limited number of
customers. Thus, the absence or presence of bulk sales has had and could have a
material impact on results of operations in any individual period.

     The Company maintains significant levels of inventory relative to its net
sales in order to meet short delivery times required by researchers. In
addition, products manufactured internally are made in economic batch sizes
which often represent quantities sufficient to supply more than one year of
sales. The Company's products generally have a relatively long shelf life, often
in excess of five years, and quality and storage conditions are continually
monitored to ensure that quality products are delivered to customers. The
Company regularly evaluates the level and composition of inventory through the
analysis of recent sales history and forecasted product demand to ensure that
inventory reserve levels are adequate to properly reflect their net realizable
value. Recent fluctuations in inventory reserve levels have not been material to
the Company's financial position or results of operations.

     The Company's reporting currency is the U.S. dollar. Historically, a
majority of the Company's sales have been denominated in U.S. dollars, with the
balance denominated in foreign currencies. These foreign currency sales have
been effected principally by the Company's international subsidiaries. In
accordance with U.S. accounting requirements, sales denominated in foreign
currencies are translated into the local functional currency and then into U.S.
dollars, at an average exchange rate in effect during the period. In addition,
the Company incurs manufacturing costs in Swiss Francs in connection with its
Swiss operations 



                                       7
<PAGE>   8

and also incurs operating expenses in local currencies at each of its other
international locations. Thus, changes from reporting period to reporting period
in the exchange rates between various foreign currencies and the U.S. dollar
have had, and will in the future continue to have, an impact on revenues and
expenses reported by the Company, and such effect may be material in any
individual reporting period. To the extent that the Company incurs operating
expenses in local currencies at its foreign subsidiaries, the Company has a
natural hedge against a portion of the possible fluctuation in foreign currency
exchange rates of billings in such currencies. Although the Company does not
engage in significant amounts of foreign currency hedging transactions, the
Company has, from time to time, entered into forward contracts to hedge certain
of its foreign currency exposures, principally related to fixed expense
commitments of its Japanese subsidiary. Additionally, the balance sheets of the
Company's international subsidiaries are translated into U.S. dollars and
consolidated with the balance sheets of the Company's domestic entities in
accordance with U.S. accounting requirements. Changes in the U.S. dollar value
of the foreign currency denominated assets are accounted for as an adjustment to
stockholders' equity. Therefore, changes from reporting period to reporting
period in the exchange rates between various foreign currencies and the U.S.
dollar have had, and will continue to have an impact on the foreign currency
translation component of stockholders' equity reported by the Company, and such
effect may be material in any individual reporting period.


     RESULTS OF OPERATIONS

     The following table sets forth, for the periods indicated, items from the
Company's Condensed Consolidated Statements of Income expressed as a percentage
of sales.

<TABLE>
<CAPTION>
                                                       PERCENTAGE OF SALES
                                              THREE MONTHS              NINE MONTHS
                                           ENDED SEPTEMBER 30,      ENDED SEPTEMBER 30,
                                           -------------------      -------------------
                                             1998      1997           1998       1997
                                             ----      ----           ----       ----
<S>                                          <C>       <C>            <C>        <C>
Sales:
  Core                                       81.4%     83.1%          81.6%      83.0%
  Bulk                                       18.6      16.9           18.4       17.0
                                            -----     -----          -----      -----
Total sales                                 100.0     100.0          100.0      100.0
Cost of sales                                44.7      44.8           44.9       44.9
                                            -----     -----          -----      -----
Gross profit                                 55.3      55.2           55.1       55.1
  Selling, general and administrative        33.2      35.3           33.0       35.5
  Research and development                    6.6       6.7            6.6        6.4
                                            -----     -----          -----      -----
Income from operations                       15.5      13.2           15.5       13.2
Interest income, net                          0.4       1.8            0.3        1.4
                                            -----     -----          -----      -----
Income before income taxes                   15.9      15.0           15.8       14.6
Provision for income taxes                    5.8       5.0            5.8        5.0
                                            -----     -----          -----      -----
     Net income                              10.1%     10.0%          10.0%       9.6%
                                            =====     =====          =====      =====
</TABLE>



                                       8
<PAGE>   9

     Three Months Ended September 30, 1998 Compared to the Three Months Ended
September 30, 1997

     Sales. Sales increased 31.2% to $12.6 million for the three-month period
ended September 30, 1998 from $9.6 million for the comparable period in 1997.
This increase resulted from a 28.5% increase in core product sales, and a 44.3%
increase in bulk sales. These gains in sales were made despite a modest
strengthening of the U.S. dollar which had the effect of decreasing the dollar
value of sales denominated in foreign currencies recorded in the three-month
period ended September 30, 1998. The increase in core product sales included the
sales of Novagen, Inc., which was acquired in December, 1997. Additional factors
which management believes contributed to the increase in sales during the period
include increased orders from the Company's recently introduced updated Novagen
general catalog and Novabiochem general catalog, and other marketing
initiatives, including advertising in various publications.

     Gross Profit. The Company's gross profit percentage increased to 55.3% for
the three-month period ended September 30, 1998 from 55.2% for the comparable
period in 1997. This increase resulted primarily from an increase in sales of
core products (including the Novagen products) offset by the the increased level
of lower margin bulk sales in the current period, and improved operating
efficiencies from increased volume and selected price increases.

     Selling, General and Administrative. Selling, general and administrative
expenses increased 23.3% to $4.2 million for the three-month period ended
September 30, 1998 from $3.4 million for the comparable period in 1997, but
decreased to 33.2% of sales for the current period from 35.3% for the comparable
period in 1997. The dollar increase in selling, general and administrative
expenses was primarily the result of incremental costs related to the Novagen
business, increased administrative salaries and selling costs related to
expanded advertising programs and additional general and specialty catalogs. The
decrease in selling, general and administrative expenses as a percentage of
sales was attributable to the increased level of sales.

     Research and Development. Research and development expenses increased 28.0%
to $832,000 for the three-month period ended September 30, 1998 from $650,000
for the comparable period in 1997, but decreased to 6.6% of sales for the
current period from 6.7% for the comparable period in 1997. The increase in
research and development expenses was primarily the result of incremental costs
related to the Novagen business, and increased research in the niche areas of
neurosciences and glycobiology. The decrease in research and development
expenses as a percentage of sales was attributable to the increased level of
sales.

     Interest income. Interest income decreased to $47,000 for the three-month
period ended September 30, 1998 from $176,000 for the comparable period in 1997.
The decrease resulted from decreased cash balances as a result of the completion
of the Novagen acquisition.

     Income Taxes. Income tax expense increased to $736,000 for the three-month
period ended September 30, 1998 from $474,000 for the comparable period in 1997.
The increase resulted from increased profitability and increased estimated tax
rates due to utilization of certain operating loss carryforwards in prior years.

     Net Income. As a result of the above factors, net income increased 32.0% to
$1,272,000 for the three-month period ended September 30, 1998 from $964,000 for
the comparable period in 1997.


     Nine Months Ended September 30, 1998 Compared to the Nine Months Ended
September 30, 1997

     Sales. Sales increased 29.8% to $38.2 million for the nine-month period
ended September 30, 1998 from $29.4 million for the comparable period in 1997.
This increase resulted from a 27.5% increase in core product sales and a 40.9%
increase in bulk sales. These gains in sales were made despite the general
strengthening of the U.S. dollar which had the effect of decreasing the dollar
value of sales denominated in foreign currencies recorded in the nine-month
period ended September 30, 1998. The increase in core 



                                       9
<PAGE>   10

product sales included the sales of Novagen, Inc., which was acquired in
December, 1997. Additional factors which management believes contributed to the
increase in sales during the period include increased orders from the Company's
recently introduced specialty catalogs for combinatorial chemistry and
glycobiology, the recently introduced Clinalfa catalog, and the recent release
of updated Novagen and Novabicohem general catalogs in 1998 and the Calbiochem
general catalog in the fourth quarter 1997. In addition, the company believes
other marketing initiatives, including advertising in various publications
contributed to the increase in sales during the period.

     Gross Profit. The Company's gross profit percentage was 55.1% for the
nine-month periods ended September 30, 1998 and 1997. This resulted primarily
from an increase in sales of core products (including the Novagen products)
offset by the increased level of lower margin bulk sales in the current period.

     Selling, General and Administrative. Selling, general and administrative
expenses increased 20.8% to $12.6 million for the nine-month period ended
September 30, 1998 from $10.4 million for the comparable period in 1997, but
decreased to 33.0% of sales for the current period from 35.5% for the comparable
period in 1997. The dollar increase in selling, general and administrative
expenses was primarily the result of incremental costs related to the Novagen
business, increased administrative salaries and selling costs related to
expanded advertising programs and additional general and specialty catalogs. The
decrease in selling, general and administrative expenses as a percentage of
sales was attributable to the increased level of sales.

     Research and Development. Research and development expenses increased 33.9%
to $2.5 million for the nine-month period ended September 30, 1998 from $1.9
million for the comparable period in 1997, and increased to 6.6% of sales for
the current period from 6.4% for the comparable period in 1997. The increase in
research and development expenses was primarily the result of incremental costs
related to the Novagen business, and increased research in the niche areas of
neurosciences and glycobiology.

     Interest income. Interest income decreased to $125,000 for the nine-month
period ended September 30, 1998 from $420,000 for the comparable period in 1997.
The decrease resulted from decreased cash balances as a result of the completion
of the Novagen acquisition.

     Income Taxes. Income tax expense increased to $2.2 million for the
nine-month period ended September 30, 1998 from $1.5 million for the comparable
period in 1997. The increase resulted from increased profitability and increased
estimated tax rates due to utilization of certain operating loss carryforwards
in prior years.

     Net Income. As a result of the above factors, net income increased 34.3% to
$3.8 million for the nine-month period ended September 30, 1998 from $2.8
million for the comparable period in 1997.


     LIQUIDITY AND CAPITAL RESOURCES

     The Company provided $245,000 of cash from operating activities in the
nine-months ended September 30, 1998, as compared to $533,000 of cash provided
by operating activities in the comparable prior period. Cash provided from
operating activities was less than net income for the nine-month periods ended
September 30, 1998 and September 30, 1997 primarily to support increases in
accounts receivable and inventory resulting from growth in core product sales.

     Net cash used in investing activities was $11.9 million in the nine-month
period ended September 30, 1998, as compared to $1.2 million in the comparable
prior period. Cash used in investing activities during the nine-month period
ended September 30, 1998 included the funding of the purchase of Novagen Inc.,
and capital expenditures related primarily to improvements to manufacturing and
distribution capabilities at various locations.

     In April 1997, the Company raised $3.2 million through the completion of a
public offering of 1,150,000 shares of Common Stock (including 910,190 shares
sold by a founding stockholder of the 



                                       10
<PAGE>   11

Company) at $13.50 per share.

     The Company is a holding company, the principal assets of which are the
capital stock of its subsidiaries, and has no independent means of generating
revenues. As a holding company, the Company depends on dividends and other
permitted payments from its subsidiaries, including its international
subsidiaries, to meet its cash needs. The Company maintains cash balances at its
various subsidiaries based upon local results of operations. The amount of
foreign-sourced earnings to be repatriated to the United States is determined
based upon foreign entity capitalization, local cash needs, local and U.S. tax
implications and requirements for cash in the U.S. operations.

     At September 30, 1998, the Company had cash, cash-equivalents and short
term investments of $7.3 million and working capital of $31.9 million. At
September 30, 1998, $5.0 million was available under a Credit Facility with a
commercial bank which expires in June 2000.

     The Company may be required to conduct business in the new European
currency (the "Euro") effective in January 1999. Management has established a
plan to convert necessary systems and marketing materials to the Euro. The
effect of the introduction of the Euro on the Company's business and results of
operations is uncertain.

     The Company believes that its existing capital resources will be adequate
to fund its operations. If, however, the Company were to undertake a significant
acquisition or if working capital or other capital requirements are greater than
currently anticipated, the Company could be required to seek additional funds
through sales of equity, debt or convertible securities or increased credit
facilities. There can be no assurance that additional financing will be
available or that, if available, will be on terms favorable to the Company and
its stockholders.


     IMPACT OF YEAR 2000

     During 1997, the Company developed a plan, and installed new operating
systems, software and computer hardware, to address anticipated Year 2000 issues
in connection with its information systems and business relationships. The plan
is divided into five phases: Awareness; Assessment; Remediation of Hardware,
Software, Equipment; Testing; and, Watch Program. At September 30, 1998, the
Awareness phase was complete and the Assessment and Remediation phases were
substantially complete. The company anticipates that all phases will be complete
by early 1999. It is currently estimated that the net cost for review, analysis,
modification and testing of existing computer programs for both internal and
external software will be between $300,000 and $500,000. The Company has
incurred a portion of such expenses in the current and prior fiscal years and it
is anticipated that a substantial portion of the remaining estimated cost will
be incurred during the remainder of this year and next year. In accordance with
generally accepted accounting principles, these costs are expensed as incurred.
The estimated costs are based on assumptions of future events, including the
continued availability of certain resources and other factors. However, there
can be no guarantee that these estimates will be reached and that actual results
will not differ materially from those in the current estimates. Specific factors
that might cause such material differences include, but are not limited to, the
availability and cost of personnel trained in this area, the ability to locate
and correct all relevant computer codes, and similar uncertainties. In addition,
the effect of Year 2000 issues on third parties with which the Company has a
material relationship is uncertain.


     FORWARD-LOOKING STATEMENTS

     This Quarterly Report on Form 10-Q contains forward-looking statements,
which involve risks and uncertainties. The Company's actual results in the
future could differ significantly from the results discussed in such
forward-looking statements. Factors that could cause or contribute to such a
difference include, but are not limited to, those set forth under the captions
Risk Factors and Management's Discussion and Analysis of Financial Condition and
Results of Operations.



                                       11
<PAGE>   12

     RISK FACTORS

     Dependence on Research and Development Budgets and Government Research
Funding. The Company's customers include research scientists at pharmaceutical
and biotechnology companies, academic institutions and government and private
research laboratories. Fluctuations in the research and development budgets of
these companies and institutions can have a significant effect on the demand for
the Company's products. Such budgets are based on a wide variety of factors
including the resources available to make such expenditures, the spending
priorities among various types of research and the policies regarding such
expenditures during recessionary periods. Any decrease in life sciences research
and development expenditures by such companies and institutions could have a
material adverse effect on the Company's business, financial condition and
results of operations.

     A significant portion of the Company's sales have been to research
scientists, universities, government research laboratories, private foundations
and other institutions whose funding is dependent on grants from government
agencies such as the U.S. National Institutes of Health ("NIH") and similar
domestic and international agencies. The funding associated with approved NIH
grants generally becomes available at particular times of the year, as
determined by the federal government, and may result in fluctuations in the
Company's operating results. Although research funding has increased during the
past several years, grants have, in the past, been frozen for extended periods
or have otherwise become unavailable to various institutions, sometimes without
advance notice. Furthermore, government proposals aiming to reduce or eliminate
budgetary deficits have in the past included reduced allocations to the NIH and
the other government agencies that fund research and development activities. If
government funding, especially NIH grants, were to become unavailable to
researchers for any extended period of time or if overall research funding were
to decrease, there could be a material adverse effect on the Company's business,
financial condition and results of operations.

     Risks Inherent in Growth, Expansion and Acquisition Strategy. The Company
has sought and will continue to seek growth in sales and profitability primarily
through the internal development and acquisition of new product lines,
additional customers and new businesses. A significant portion of the Company's
historical revenue growth is attributable to internal product development,
sourcing of third-party products and more recently from its acquisition of
Novagen, Inc. The ability of the Company to achieve its expansion objectives and
to manage its growth effectively depends upon a variety of factors, including
(i) the ability to internally develop products, (ii) the ability to identify and
license products sourced from third parties, (iii) the ability to successfully
position and market its products, (iv) the ability to identify and consummate
attractive acquisitions and (v) the ability to integrate new businesses,
facilities and personnel into existing operations. If the Company is unable to
manage growth effectively, there could be a material adverse effect on the
Company's business, financial condition and results of operations.

     The Company competes for acquisition and expansion opportunities with other
companies that have significantly greater financial and other resources than
those of the Company. There can be no assurance that suitable acquisition or
investment opportunities will be identified, consummated, or, if consummated,
integrated successfully and profitably into the Company's operations. Moreover,
there can be no assurance that the Company's historic rate of growth or
expansion will continue, or that further growth or expansion will result in
continued profitability. The Company successfully completed the purchase of
Novagen, Inc. in December 1997. Although management expects to be able to
integrate the business activities of Novagen into its existing marketing and
distribution facilities and to gain synergies and growth, there can be no
assurance that such integration will be successful or that sales and profits
will increase. If the Company is unable to integrate Novagen, there could be a
material adverse effect on the Company's business financial condition and
results of operations.

     Reliance on Niche Research Market Strategy. Key elements of the Company's
strategy include the targeting and penetration of emerging life sciences niche
research markets and the continued development of the niche research markets
currently served by the Company. If the Company is unable to successfully target
and penetrate these niche research markets or is unable to continue developing
the niche research markets currently served or if the Company's new products are
not accepted by research scientists, there 



                                       12
<PAGE>   13

could be a material adverse effect on the Company's business, financial
condition and results of operations. In addition, the Company currently benefits
from its participation in emerging niche research markets which, as they expand,
may attract the attention of the Company's competitors. Further, as these niche
research markets mature, products that were once innovative, thus commanding
higher margins, may become commodities.

     Dependence on New Products; Rapid Technological Change. The life sciences
research products market is characterized by rapid technological change and
frequent product introductions. The Company's future success will depend, in
part, on its ability to develop and introduce, on a timely basis, products that
address the evolving needs of its customers. There can be no assurance that the
Company will not experience difficulties that could delay or prevent the
successful development, introduction and marketing of products. The Company has
experienced, and may in the future experience, delays in the development and
introduction of products, and there can be no assurance that the Company will
keep pace with the rapid rate of change in life sciences research, and will not
experience additional delays in the future. In addition, there can be no
assurance that new products will adequately meet the requirements of the
marketplace or achieve market acceptance. Factors affecting whether such
products will be accepted by the market include use of the product by research
scientists, citation of the product in published research, the timing of market
entry of the product relative to competitive products and general trends in life
sciences research. If the Company is unable, for technological or other reasons,
to develop and introduce products in a timely manner in response to changing
market environments or customer requirements, there could be a material adverse
effect on the Company's business, financial condition and results of operations.

     Dependence on Licensing as a Source of Products. Many of the Company's
products are manufactured or sold pursuant to license agreements under which the
Company pays royalties to the patent holder based upon a percentage of the
product's sales. There can be no assurance that the Company will be able to
continue to successfully identify new products developed by others, and if
identified, to negotiate license agreements on favorable terms. Additionally,
there can be no assurance that the Company will be able to renew any existing
license agreements upon their expiration.

     Highly Competitive Market. The market for the Company's products is highly
competitive, and the Company expects competition to increase. Furthermore,
although the life sciences research products market continues to grow, its rate
of growth in recent years has been declining and may continue to decline. The
Company competes with many other life sciences research products suppliers, both
larger and smaller than the Company. Some of the Company's competitors,
including two of its largest competitors, Sigma-Aldrich Corporation and Roche
Molecular Biochemicals, offer a broad range of equipment, laboratory supplies
and other products, including many of the research products offered by the
Company. To the extent that researchers exhibit loyalty to the supplier that
first supplies them with a particular research product, the Company's
competitors may have an advantage over the Company with respect to products
first developed by such competitors. In addition, many of the Company's
competitors have significantly greater research and development, marketing,
financial and other resources than the Company, and therefore represent and will
continue to represent significant competition in the Company's existing and
future markets. Because of their size and the breadth of their product
offerings, certain of these companies have been able to establish managed
accounts by which, through a combination of direct computer links and volume
discounts, they seek to gain a disproportionate share of orders for research
products from particular academic institutions or pharmaceutical or
biotechnology companies. Such managed accounts raise significant competitive
barriers for the Company. The Company currently benefits from its participation
in emerging niche research markets which, as they expand, may attract the
attention of the Company's competitors.

     Reliance on Catalogs, Distributors and Direct Marketing Efforts; Limited
Sales Force. The Company sells its products principally through catalogs
distributed to research scientists and laboratories, and uses only a very
limited number of salespeople in certain of its markets. There can be no
assurance that the Company would be able to successfully establish other methods
of marketing and sales of its products should it become necessary or desirable
in the future. Additionally, the Company's catalogs are generally reissued every
12 to 24 months and price adjustments between catalog publication dates have
historically been infrequent. A significant portion of the Company's
international sales are made through independent distributors over which the
Company has no control and who also represent products of other companies. 



                                       13
<PAGE>   14

The loss of any of these distribution methods could have a material adverse
effect on the Company's business, financial condition and results of operations.

     Volatility of Bulk Sales Business. In addition to sales of its core
products in standard laboratory quantity sizes (generally ranging from 100
nanograms to 100 grams), the Company offers certain products in bulk quantities
(generally up to ten kilograms) at discounts from catalog prices. Bulk sales,
which represented 18.6% of net sales during the quarter ended September 30,
1998, are generally characterized as relatively high dollar sales made to a
limited number of customers. Thus, the absence or presence of a bulk sale could
have a material impact on quarterly results. Furthermore, the Company's bulk
sales business fluctuates more and is less predictable than its core business,
and the uncertain timing and volatility of bulk sales has in the past and may
continue in the future to materially affect the Company's business, financial
condition and results of operations.

     Significant Fluctuations in Quarterly Earnings. The Company's quarterly
operating results may vary significantly from quarter to quarter as a result of
a number of factors including new editions of existing catalogs, introduction of
additional specialty catalogs and bulk sales of the Company's products. Other
factors which may affect quarterly operating results include the timing of the
U.S. Government approval of the NIH budget, lower European and academic sales
during the summer months and various holiday breaks and fluctuations in weather.
The Company's current and planned expense levels are based in part upon its
expectations as to future revenues. Consequently, if revenues in a particular
quarter do not meet expectations, the Company may not be able to adequately
adjust operating expenses to compensate for the shortfall. Operating results may
therefore vary significantly from quarter to quarter and will not necessarily be
indicative of results in subsequent periods.

     Uncertainty of Future Operating Results. Although the Company had net
income for 1995, 1996 and the first three quarters of 1998, the Company incurred
a net loss for the year ended December 31, 1997 due to a one time write-off of
in-process technology associated with the acquisition of Novagen, Inc. Future
operating results will depend on many factors, including demand for the
Company's products, the levels and timing of government and private sector
funding of life sciences research and development activities, the timing of the
introduction of products and catalogs by the Company or its competitors, and the
Company's ability to control costs. Furthermore, the Company's gross margins can
be significantly affected by the presence or absence of bulk sales during any
particular period and quarterly fluctuations in sales relative to operating
expenses. There can be no assurance that the Company will be able to grow in
future periods or remain profitable.

     Risks Relating to International Sales and Operations. Historically, product
sales to customers outside the United States have accounted for approximately
50% of the Company's net sales, and the Company expects that international sales
will continue to account for a significant percentage of revenues in the future.
International sales and operations may be materially adversely affected by trade
restrictions, changes in tariffs and taxes, export license requirements,
difficulties in staffing and managing international operations, difficulties in
converting systems and marketing materials to the Euro, market acceptance of the
Euro, problems in establishing or managing distributor relationships and general
economic conditions.

     A majority of the Company's sales are denominated in U.S. dollars, with the
balance denominated in foreign currencies. Additionally, the Company publishes a
number of its catalogs priced in foreign currencies and price adjustments
between catalog publication dates to reflect fluctuations in the value of
foreign currencies relative to the U.S. dollar have historically been
infrequent. Consequently, fluctuations in the value of foreign currencies
relative to the U.S. dollar, the introduction of the Euro in January of 1999,
and changes in general international economic conditions including market
acceptance of the Euro could have a material adverse effect on the Company's
business, financial condition and results of operations.

     Risk of Patent Infringement. Because of the breadth of the Company's
product offerings and ambiguities in intellectual property law, the Company
periodically receives in the ordinary course of business notices of potential
infringement of patents held by others. Although the Company historically has
been able to satisfactorily resolve such claims and believes that any
outstanding claims will be satisfactorily resolved, there can be no assurance
that the Company may not be forced to discontinue the sale of one or 



                                       14
<PAGE>   15

more of its products, some or all of which could be material. Additionally, the
Company believes that the molecular biology area, in which Novagen, its newly
acquired brand, competes, has a higher incidence of involvement in patent
disputes. As the Company develops product offerings focused on certain niche
research markets, intellectual property rights of the Company or others related
to such markets may become increasingly important, and the Company's failure to
obtain and retain such rights may have a material adverse effect on the
Company's business, financial condition and results of operations.

     Dependence on Key Personnel. The Company's future success depends in
significant part on the continued service of, and on the Company's continuing
ability to attract and retain, highly qualified technical, managerial and sales
personnel. Competition for such personnel is intense in the Company's industry
and geographic locations, and there can be no assurance that the Company will be
able to retain or attract such employees in the future. The loss of key
personnel or the inability to hire or retain qualified personnel could have a
material adverse effect on the Company's business, financial condition and
results of operations. The Company has entered into employment agreements with
Stelios B. Papadopoulos, its Chairman, Chief Executive Officer and President,
and Ben Matzilevich, its Vice President, Market Development --Niche
Applications.

     Risk Relating to the Influence of the Internet on Marketing and Catalogs.
The Internet has begun to change marketing patterns in a wide variety of
industries. The high degree of personal computer usage within scientific
research organizations may lead to entirely new methods of marketing and sales
of research products. While the Company has established home pages on the
Internet for the Calbiochem, Novabiochem, Oncogene Research Products and Novagen
brands, the Company may not be able to keep pace with the rate of change in its
markets brought about by the Internet and may invest in catalogs or
Internet-based projects which future changes may render obsolete.

     Compliance with Government and Environmental Regulations. The Company is
subject to various forms of government regulations, including environmental and
safety laws and regulations and laws governing use and storage of hazardous
materials. The Company has in the past been notified of minor violations of
government and environmental regulations. The Company has promptly corrected
such violations without any material impact on the Company's operations. Any
future violation of, and the cost of compliance with, these laws and regulations
could have a material adverse effect on the Company's business, financial
condition and results of operations.

     Because of the nature of its operations and the use of hazardous substances
in its ongoing manufacturing and research and development activities, the
Company is subject to stringent federal, state and local laws, rules,
regulations and policies governing the use, generation, manufacturing, storage,
air emission, effluent discharge, handling and disposal of certain materials and
wastes. Prior to the Company's inception, its U.S. subsidiary, at the time it
was owned by its former owners, was involved in two separate incidents related
to the release of hazardous materials into the environment at a leased facility
which is no longer occupied by the Company. The Company believes from a review
of correspondence from various regulatory agencies that these incidents were
investigated and remediated by the U.S. subsidiary's former owners. Although the
Company believes it is in material compliance with all applicable government and
environmental laws, rules, regulations, and policies, there can be no assurance
that the Company's business, financial condition and results of operations will
not be materially adversely affected by current or future environmental laws,
rules, regulations and policies or by liability arising out of any past or
future releases or discharges of materials that could be hazardous.

     Product Liability Risk; Limited Insurance Coverage. Although the Company
does not sell products intended for use in humans, or, with the exception of its
Clinalfa products, sell products intended for use in human clinical trials, the
Company's business could expose it to potential liability risks. The Company
currently has only limited product liability insurance, and there can be no
assurance that it will be able to maintain such insurance or obtain additional
insurance on acceptable terms or that insurance will provide adequate coverage
against potential liabilities. A successful product liability claim or a series
of claims brought against the Company in excess of its insurance coverage limits
could have a material adverse effect on the Company's business, financial
condition and results of operations.



                                       15
<PAGE>   16

     Holding Company Structure. The Company is a holding company, the principal
assets of which are certain cash balances and the capital stock of its
subsidiaries, and has no independent means of generating operating revenues. As
a holding company, the Company depends primarily on dividends and other
permitted payments from its subsidiaries, including its international
subsidiaries, to meet its cash needs. The Company maintains cash balances at its
various subsidiaries adequate to support local operations. The amount of
foreign-sourced earnings to be repatriated to the United States is determined
based upon foreign entity capitalization, local cash needs, local and U.S. tax
implications and requirements for cash in the U.S. operations.

     Substantial Influence of Principal Stockholder. The Company's principal
stockholder, Warburg, Pincus Investors, L.P. ("Warburg") beneficially owns
approximately 40% of the Company's Common Stock, par value $.01 per share (the
"Common Stock"). Because of such ownership, Warburg has substantial influence
over the election of all members of the Board of Directors and corporate actions
requiring stockholder approval. Additionally, pursuant to an agreement with the
Company, Warburg has certain rights to nominate directors as long as it
continues to own specified percentages of the outstanding shares of Common
Stock.

     Anti-Takeover Provisions. Under the Company's Amended and Restated
Certificate of Incorporation (the "Certificate of Incorporation"), the Company's
Board of Directors has the authority to issue up to 5,000,000 shares of
Preferred Stock and to determine the price, rights, preferences and privileges
of those shares without any further vote or action by the stockholders. 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, while providing desirable
flexibility in connection with possible acquisitions and other corporate
purposes, could have the effect of making it more difficult for a third party to
acquire a majority of the outstanding voting stock of the Company. The Company
has no present plans to issue shares of Preferred Stock. The Company is also
subject to the provisions of Section 203 of the Delaware General Corporation
Law, an anti-takeover law. Additionally, the Company has entered into severance
arrangements with each of its executive officers which provide, among other
things, for severance payments if, within 90 days of a "change in control" of
the Company (as defined in the applicable agreements), the executive's
employment is terminated other than for cause or the executive resigns. Such
arrangements could have an anti-takeover effect.


Item 3. Quantitative and Qualitative Disclosures About Market Risk

     Not required.














                                       16
<PAGE>   17

                           PART II - OTHER INFORMATION

Item 6. Exhibits and Reports on Form 8-K.

     (a)  Exhibits:

          3(a) Amended and Restated Certificate of Incorporation*

          3(b) Amended and Restated By-Laws*

         10(w) Agreement of Sublease by and between Trustees of Boston
                 University and Calbiochem-Novabiochem Corporation dated as
                 of July 8, 1998.

          11   Statement re computation of per share earnings

          27   Financial Data Schedule

     (b)  Reports on Form 8-K:

          No reports on Form 8-K were filed by the Registrant during the three
          months ended September 30, 1998. 

- ----------
* Incorporated by reference from the Registrant's Form 10-Q for the quarterly 
  period ended September 30, 1996 (File No. 000-21281)













                                       17
<PAGE>   18

                                   SIGNATURES


Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.


                                       CN BIOSCIENCES, INC.



November 10, 1998                      /s/ Stelios B. Papadopoulos
                                       -----------------------------------------
                                       Stelios B. Papadopoulos
                                       Chief Executive Officer, Chairman
                                       and President
                                       (duly authorized officer)


November 10, 1998                      /s/ James G. Stewart
                                       -----------------------------------------
                                       James G. Stewart
                                       Vice President, Chief Financial Officer
                                       and Secretary
                                       (principal financial officer)










                                       18
<PAGE>   19

                                INDEX OF EXHIBITS


<TABLE>
<CAPTION>
Exhibit Number   Description
- --------------   -----------
<S>              <C>
3(a)             Amended and Restated Certificate of Incorporation*

3(b)             Amended and Restated By-Laws*

10(w)            Agreement of Sublease by and between Trustees of Boston
                 University and Calbiochem-Novabiochem Corporation dated as of
                 July 8, 1998.

11               Statement re computation of per share earnings

27               Financial Data Schedule
</TABLE>
- ----------
* Incorporated by reference from the Registrant's Form 10-Q for the quarterly 
  period ended September 30, 1996 (File No. 000-21281)














                                       19

<PAGE>   1
                                                                  EXHIBIT 10(W)

                                                                  Execution Copy



                              AGREEMENT OF SUBLEASE

                                 by and between

                          TRUSTEES OF BOSTON UNIVERSITY

                                       and

                       CALBIOCHEM-NOVABIOCHEM CORPORATION

                            Dated as of July 8, 1998



<PAGE>   2



                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
SECTION                                                                                            PAGE
<S>               <C>                                                                              <C>

1.       DESCRIPTION OF THE SUBLEASE PREMISES

         1.1      Sublease Premises..............................................................   1
         1.2      Appurtenant Rights.............................................................   2
         1.3      Exclusions and Reservations....................................................   2

2.       TERM OF LEASE

         2.1      Habendum.......................................................................   2
         2.2      Term Commencement Date.........................................................   3
         2.3      Option to Extend Term..........................................................   3
         2.4      Fair Market Rent...............................................................   3
         2.5      Parking........................................................................   4
         2.6      Security Deposit...............................................................   6

3.       CONSTRUCTION

         3.1      Initial Construction...........................................................   8
         3.1A     Approval and Removal...........................................................  10
         3.1B     Decommission...................................................................  11
         3.2      Preparation of Premises for Occupancy..........................................  11
         3.2A     Delay in Term Commencement Date................................................  11
         3.2B     Delay in Foundation Date.......................................................  12
         3.3      General Provisions Applicable to Construction..................................  13
         3.4      Force Majeure Delays...........................................................  13
         3.5      Tenant Delays..................................................................  13
         3.6      Access During Construction.....................................................  14
         3.7      Signage........................................................................  14

4.       USE OF THE SUBLEASE PREMISES

         4.1      Permitted Uses.................................................................  15
         4.2      Prohibited Uses................................................................  16
         4.3      Licenses and Permits...........................................................  17
         4.4      Equipment......................................................................  18
         4.5      Access.........................................................................  18
         4.6      Extra Hazardous Use............................................................  18

5.       RENT; UTILITIES

         5.1      Yearly Fixed Rent..............................................................  20
         5.2      Additional Rent................................................................  20
</TABLE>

                                       ii

<PAGE>   3

<TABLE>
<S>               <C>                                                                              <C>
         5.2A     Tax and Tax Fund Payments......................................................  23
         5.3      Utilities......................................................................  25
         5.4      Interruption or Curtailment of Services........................................  26
         5.5      Payment to Mortgagee...........................................................  27
         5.6      Utility Deregulation...........................................................  27
         5.7      HVAC Services..................................................................  28
         5.8      Sublessor Services.............................................................  29
         5.9      Additional Rent................................................................  29
         5.10     Government Award or Grant......................................................  30

6.       CHANGES OR ALTERATIONS BY SUBLESSOR.....................................................  30

7.       FIXTURES, EQUIPMENT AND IMPROVEMENTS - REMOVAL BY SUBLESSEE.............................  31

8.       ALTERATIONS AND IMPROVEMENTS BY SUBLESSEE...............................................  31

9.       SUBLESSOR'S CONTRACTORS-MECHANICS' AND OTHER LIENS-STANDARD OF
         SUBLESSEE'S PERFORMANCE-
         COMPLIANCE WITH LAWS....................................................................  32

10.      REPAIRS AND SECURITY BY SUBLESSEE.......................................................  33

11.      INSURANCE, INDEMNIFICATION, EXONERATION
         AND EXCULPATION.........................................................................  34

         11.1     Insurance......................................................................  34
         11.2     Certificates of Insurance......................................................  34
         11.3     General........................................................................  34
         11.4     Property of Sublessee..........................................................  35
         11.4A    Release and Waiver of Subrogation..............................................  36
         11.5     Bursting of Pipes, etc.........................................................  36
         11.6     Repairs and Alterations-No Diminution of Rental Value..........................  36
         11.7     Sublessor's Insurance..........................................................  37

12.      ASSIGNMENT, MORTGAGING, SUBLETTING, ETC.................................................  37

13.      MISCELLANEOUS COVENANTS.................................................................  40

         13.1     Rules and Regulations..........................................................  40
         13.2     Access to Premises - Shoring...................................................  40
         13.3     Accidents to Sanitary and other Systems........................................  41
         13.4     Signs, Blinds and Drapes.......................................................  41
         13.5     Estoppel Certificate...........................................................  42
         13.6     Prohibited Items...............................................................  42
         13.7A    Requirements of Law-Fines and Penalties........................................  42
</TABLE>


                                      iii

<PAGE>   4

<TABLE>
<S>               <C>                                                                              <C>
         13.7B    Structural Items...............................................................  42
         13.8     Sublessee's Acts-Effects on Insurance..........................................  43
         13.9     Authority......................................................................  43
         13.10    Miscellaneous..................................................................  43

13A.     SUBLESSOR REPRESENTATIONS...............................................................  44

14.      DAMAGE BY FIRE AND CONDEMNATION.........................................................  44

14A.     DAMAGE BY FIRE..........................................................................  44

14B.     CONDEMNATION............................................................................  46

15.      DEFAULT AND ENFORCEMENT.................................................................  47

         15.1     Conditions of Limitation-Re-entry-Termination..................................  47
         15.2     Damages-Assignment for Benefit of Creditors....................................  48
         15.3     Damages-Termination............................................................  49
         15.4     Fees and Expenses..............................................................  50
         15.5     Sublessor's Remedies Not Exclusive.............................................  50
         15.6     Grace Period...................................................................  50

16.      END OF TERM-ABANDONED PROPERTY; HOLDOVER................................................  51

17.      SUBLEASE SUBORDINATE....................................................................  52

18.      QUIET ENJOYMENT.........................................................................  52

19.      ENVIRONMENTAL INDEMNITY.................................................................  53

20.      ENTIRE AGREEMENT-WAIVER-SURRENDER.......................................................  54

         20.1     Entire Agreement...............................................................  54
         20.2     Waiver.........................................................................  55
         20.3     Surrender......................................................................  55

21.      INABILITY TO PERFORM-EXCULPATORY CLAUSE.................................................  55

22.      BILLS AND NOTICES.......................................................................  56

23.      PARTIES BOUND-SEIZING OF TITLE..........................................................  58

24.      SUBLESSEE EFFORTS REGARDING MINORITY PARTICIPATION......................................  58

25.      FIRST RIGHT OF REFUSAL..................................................................  59
</TABLE>


                                       iv

<PAGE>   5

<TABLE>
<S>               <C>                                                                              <C>
26.      MISCELLANEOUS...........................................................................  59

         26.1     Separability...................................................................  59
         26.2     Captions.......................................................................  60
         26.3     Broker.........................................................................  60
         26.4     Governing Law..................................................................  60
         26.5     Time of the Essence............................................................  60
         26.6     Notice of Sublease.............................................................  60
         26.7     Relationship between Sublessor and Sublessee...................................  60
         26.8     Transfer.......................................................................  60
         26.9     Financial Capability...........................................................  60
         26.10    Notice to Mortgagee............................................................  61
         26.11    Attorneys' Fees................................................................  61
         26.12    Subordination, Non-Disturbance and Attornment Agreement........................  61
</TABLE>

                                       v

<PAGE>   6


                              SCHEDULE OF EXHIBITS


<TABLE>
<S>                   <C>
Exhibit A             The Legal Description of the Lot

Exhibit A-2           Parking Facility Map

Exhibit B             Ground Floor Premises

Exhibit C             Second Floor Premises

Exhibit D             Guaranty

Exhibit E             Certificate verifying the square footage of the Sublease 
                      Premises and Main Premises and Commencement Date

Exhibit F             Work Letter Agreement

Exhibit F-1           Intentionally Omitted

Exhibit F-2           Base Building Work Schedule

Exhibit G             Environmental Report

Exhibit H             First Source Agreement

</TABLE>

                                       vi


<PAGE>   7
                                                                  Execution Copy

                              AGREEMENT OF SUBLEASE

         This Agreement of Sublease ("Sublease") dated as of the 8th day of
July, 1998 by and between Trustees of Boston University, a Massachusetts
non-profit educational corporation with an address at 715 Albany Street, Boston,
Massachusetts 02118 ("Sublessor") and Calbiochem-Novabiochem Corporation, a
California corporation with an address at c/o CN Biosciences, Inc., 10394
Pacific Center Court, San Diego, CA 92121 ("Sublessee").

                                WITNESSETH THAT:

         WHEREAS, pursuant to an Agreement of Lease dated as of June 26, 1998
between Richard Moed and Kenneth G. Condon, as Trustees of The 650 Albany Street
Medical Realty Trust, a Massachusetts nominee trust under declaration of trust
dated June 24, 1998 and to be recorded with Suffolk Registry of Deeds, as
Landlord ("Landlord"), and Trustees of Boston University, as Tenant (the "Main
Lease"), Landlord leased to Sublessor, as Tenant, approximately 69,161.72
rentable square feet of space (the "Main Premises") located on the ground,
second and third floors and a portion of another floor contained in the building
to be known and numbered as 650 Albany Street, Boston, Massachusetts 02118
(Biosquare, Building "C") (the "Building"), located on a lot, the legal
description of which lot is attached hereto as Exhibit A (the "Lot" or
"Property"); and

         WHEREAS, Sublessor has agreed to sublease approximately 28,446 rentable
square feet of the Main Premises, which space is shown on Exhibits B and C
attached hereto (the "Sublease Premises"), to Sublessee on the terms stated
herein; and

         WHEREAS, Sublessee has agreed to cause its parent, CN Biosciences,
Inc., a Delaware corporation ("Guarantor"), to deliver to Sublessor as
additional consideration for this Sublease a guaranty, the form of which is
attached hereto as Exhibit D (the "Guaranty"), to Sublessor on even date
herewith;

         NOW, THEREFORE, in consideration of the mutual covenants herein
contained and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, Sublessor and Sublessee hereby
agree as follows:

1.       DESCRIPTION OF THE SUBLEASE PREMISES

         1.1 Sublease Premises. Sublessor hereby leases and demises to Sublessee
and Sublessee hereby hires and takes from Sublessor the Sublease Premises. The
Sublease Premises are comprised of approximately 28,446 rentable square feet of
space in the Building and are described as follows:

         a. A portion of the ground floor of the Building containing
approximately 16,874 rentable square feet of space as more particularly shown on
a plan attached hereto as Exhibit B (the "Ground Floor Premises").


<PAGE>   8


         b. A portion of the second floor of the Building containing
approximately 11,572 rentable square feet of space as more particularly shown on
a plan attached hereto as Exhibit C (the "Second Floor Premises").

The Ground Floor Premises and the Second Floor Premises shall be herein referred
to collectively as the "Sublease Premises".

         1.2 Appurtenant Rights. Sublessee shall have, as appurtenant to the
Sublease Premises, rights to use in common with Sublessor and Landlord and other
occupants of the Building, subject to reasonable and uniform rules from time to
time made by Landlord or Sublessor of which Sublessee is given prior written
notice, those common roadways, walkways, elevators, lobbies, hallways and
stairways necessary or convenient for access to that portion of the Building
occupied by the Sublease Premises together with all other common areas and
facilities of the Building and the Lot.

         1.3 Exclusions and Reservations. All the perimeter walls of the
Sublease Premises except the inner surfaces thereof, any balconies, terraces or
roofs adjacent to the Sublease Premises, and any space in or adjacent to the
Sublease Premises used for shafts, stacks, pipes, conduits, wires and
appurtenant fixtures, ducts, electric or other utilities, tele-communications
equipment or other Building facilities, and the use thereof, as well as the
right of access (which right of access shall be at reasonable times and upon
reasonable notice, except in the case of emergency) through the Sublease
Premises for the purpose of operation, maintenance and repair, are expressly
reserved to Landlord. The rentable square footage of the Sublease Premises shall
be measured according to BOMA standards and shall be confirmed and verified by
the architect for the Building in consultation with Sublessee's space planner.
The square footage of the Sublease Premises as determined in accordance with the
foregoing sentence shall be binding on Sublessor and Sublessee. Sublessor and
Sublessee agree to sign a certificate in the form attached hereto as Exhibit E
verifying the square footage of the Sublease Premises, the Main Premises and the
Building. Failure of either Sublessor or Sublessee to remeasure the Sublease
Premises, the Main Premises and the Building on or before thirty (30) days after
the Term Commencement Date (as hereinafter defined) shall be deemed a waiver by
such party as to its right to remeasure and accordingly, if the parties do not
remeasure the Sublease Premises, the Main Premises and the Building, the parties
agree to be bound by the Sublease Premises, the Main Premises and the Building
measurements as set forth herein.

2.       TERM OF LEASE

         2.1 Habendum. TO HAVE AND TO HOLD the Sublease Premises for a term of
ten years commencing on the Term Commencement Date (as hereinafter defined) and
ending on the day immediately prior to the tenth anniversary thereof (the "Term
of this Sublease" or "Original Term"), or on such earlier date upon which said
Term may expire or be cancelled or be terminated pursuant to any of the
conditions of limitation or other provisions of this Sublease or pursuant to
law, subject to Sublessee's options to extend said Term in accordance with the
provisions of Section 2.3 (which date for the expiration, 



                                       2
<PAGE>   9

cancellation or termination of the Term hereof shall hereafter be called the
"Termination Date").

         2.2 Term Commencement Date. The Term Commencement Date shall be the
earlier of (a) the date on which the Sublease Premises are deemed ready for
occupancy as provided in Section 3.2 or (b) the date on which Sublessee occupies
all or any part of the Sublease Premises for the Permitted Uses.

         2.3 Option to Extend Term. So long as Sublessee is not, on the date
upon which the Sublessee exercises the applicable extension option and at the
commencement of the applicable extension period, in default under the provisions
of this Sublease beyond the applicable grace period set forth herein, if any,
Sublessee may extend the Term of this Sublease for two periods, each period to
be five years (referred to herein as the "first extension period" and the
"second extension period"), by giving notice to Sublessor of its election to
extend at least twelve months in advance of the commencement of the applicable
extension period. Prior to the exercise by Sublessee of either such option, the
expression "Term" shall mean the original ten-year term, and after the exercise
by Sublessee of any such option, the expression "Term" shall mean the Original
Term as it may have then been extended. Except as otherwise hereinafter set
forth, all terms and conditions of this Sublease shall remain in full force and
effect with respect to such extension period. If Sublessee shall give notice of
its exercise of either such option to extend in the manner and within the time
period provided aforesaid, the Term shall be extended upon the giving of such
notice without the requirement of any further action on the part of either
Sublessor or Sublessee.

         With respect to each such extension period, (i) the Yearly Fixed Rent,
as defined in Section 5.1 hereof, payable during such extension period shall be
the fair market rent as of the commencement of such extension period determined
in accordance with the provisions of Section 2.4 hereof, (ii) the Additional
Rent, as defined in Section 5.2 hereof, payable during such extension period
shall be adjusted to reflect Sublessee's pro rata share of all such Additional
Rent then incurred by Sublessor in the operation and maintenance of the Building
and the Lot based on the rentable square footage of the Sublease Premises in
relation to the rentable square footage of the Building ("Sublessee's
Proportionate Share") and (iii) Parking Rent, as defined in Section 2.5 hereof,
payable during such extension period shall be the fair market rent as of the
commencement of such extension period determined in accordance with the
provisions of Section 2.4 hereof. In addition to the foregoing, with respect to
each such extension period, Sublessee shall continue to pay Additional Rent for
Taxes, as defined in Section 5.2A hereof, all utility expenses as set forth
herein and any other costs and expenses set forth herein.

         2.4 Fair Market Rent. "Fair market rent" shall mean the fair market
rent for the subject space as of the commencement of the period in question
under market conditions then existing. Fair market rent shall be determined by
agreement between Sublessor and Sublessee or their representatives, but if
Sublessor and Sublessee are unable to agree upon the fair market rent at least
ten months prior to the date upon which the fair market rent is to take effect,
then the fair market rent shall be determined by appraisal made as hereinafter
provided by a board of three reputable independent MAI certified real estate
appraisers, each 



                                       3
<PAGE>   10

of whom shall have at least ten years of experience in the appraisal of research
and office space in the metropolitan Boston area. Sublessee and Sublessor shall
each appoint one such appraiser and the two appraisers so appointed shall
appoint the third appraiser. The cost and expenses of each appraiser appointed
separately by Sublessee and Sublessor shall be borne by the party who appointed
the appraiser. The cost and expenses of the third appraiser shall be shared
equally by Sublessee and Sublessor. Sublessor and Sublessee shall appoint their
respective appraisers at least nine months prior to the commencement of the
period for which fair market rent is to be determined and shall designate the
appraisers so appointed by notice to the other party. The two appraisers so
appointed and designated shall appoint the third appraiser at least eight months
prior to the commencement of such period and shall designate such appraiser by
notice to Sublessor and Sublessee. The board of three appraisers shall determine
the fair market rent of the space in question as of the commencement of the
period to which the fair market rent shall apply, which determination shall
include the value of the Sublease Improvements (as defined in Section 3.1
hereof). The appraisers shall notify Sublessor and Sublessee of their
determinations at least seven months prior to the commencement of such period.
If the determinations of the fair market rent of any two or all three of the
appraisers shall be identical in amount, said amount shall be deemed to be the
fair market rent of the subject space. If the determinations of all three
appraisers shall be different in amount, the average of the two values nearest
in amount shall be deemed the fair market rent. The fair market rent of the
subject space determined in accordance with the provisions of this Section shall
be binding and conclusive on Sublessor and Sublessee. Notwithstanding the
foregoing, if either party shall fail to appoint its appraiser within the period
specified above (such party referred to hereinafter as the "failing party"), the
other party may serve notice on the failing party requiring the failing party to
appoint its appraiser within ten days of the giving of such notice and if the
failing party shall not respond by appointment of its appraiser within said
ten-day period, then the appraiser appointed by the other party shall be the
sole appraiser whose determination of the fair market rent shall be binding and
conclusive upon Sublessee and Sublessor.

         Judgment on the determination made under the foregoing provision may be
entered in any court of competent jurisdiction pursuant to the provisions of
Section 14 of Chapter 251 of the General Laws of Massachusetts.

         Notwithstanding anything contained in this Section 2.4 or anywhere else
in this Sublease to the contrary, in no event shall the Yearly Fixed Rent for
any extension term be less than (a) $29.00 per rentable square foot of the
Sublease Premises per annum for the first extension period or (b) $32.00 per
rentable square foot of the Sublease Premises per annum for the second extension
period.

         2.5 Parking. Sublessee shall be entitled to lease up to, but in no
event at any time during the Term of this Sublease more than, two (2)
non-reserved parking spaces in the surface parking lots and garages serving the
Boston University Medical Center, as designated from time to time by Sublessor
during the Term of this Sublease (the "Parking Facility"), for every 1,000
square feet of rentable square feet of Sublease Premises. The Parking Facility
will be located from time to time in the cross hatched area in the Biosquare
Project Area shown on the Parking Facility Map, a copy of which Parking Facility
Map is 



                                       4
<PAGE>   11

attached hereto as Exhibit A-2. Sublessor shall deliver such non-reserved
parking spaces to Sublessee in accordance with the terms hereof. The parking
spaces may be used by Sublessee twenty-four (24) hours a day and 365/366 days a
year.

         Sublessor shall use reasonable efforts to notify Sublessee in writing
("Sublessor's Notification") that it believes in good faith that the Term
Commencement Date will occur approximately sixty (60) days from the date of such
notification. No later than thirty (30) days after Sublessee's receipt of
Sublessor's Notification, time being of the essence, Sublessee must designate in
writing the number of parking spaces it elects to lease for the first year of
the Term (hereinafter "the First Year leased parking spaces"). No later than ten
(10) months after the Term Commencement Date, time being of the essence,
Sublessee must designate in writing the number of parking spaces it elects to
lease for the remainder of the Term (hereinafter "the leased parking spaces for
the remainder of the Term"), and such number of spaces shall be effective as of
the first anniversary of the Term Commencement Date and shall be the number of
parking spaces for the remainder of the Term except as otherwise specifically
provided herein. Failure by Sublessee to make such elections in accordance with
the foregoing sentences shall constitute a waiver by Sublessee to lease parking
spaces. Except for particular spaces and areas designated by Landlord for
reserved parking, all parking in the Parking Facility shall be on an unreserved,
first-come, first-served basis. Sublessee acknowledges that Landlord shall have
the right to operate the Parking Facility through the use of valet parking.
Sublessee shall have the right to irrevocably relinquish parking spaces during
the Term provided Sublessee gives Sublessor not less than thirty (30) days prior
written notice of the number of parking spaces Sublessee elects to relinquish
and the date upon which Sublessee shall irrevocably relinquish any parking
space(s), which date of relinquishment shall always occur on the last day of a
month.

         The lease of the parking spaces shall be on the following terms and
conditions:

                a.      Sublessee shall pay Sublessor market rate rent for each
                        parking space leased by Sublessee. The initial market
                        rate ("Parking Rent") per parking space per month for
                        the first two lease years of the Term shall be $90.00.
                        Commencing with the third lease year, such Parking Rent
                        shall be adjusted to market rate rent. During each of
                        the third, fourth and fifth lease years of the Term, any
                        yearly increase in Parking Rent shall not be in excess
                        of 5% of the prior lease year's Parking Rent and during
                        lease years six through ten, any yearly increase in
                        Parking Rent shall not be in excess of 7% of the prior
                        lease year's Parking Rent

                b.      Sublessor and Landlord shall not be responsible for
                        money, jewelry, automobiles or other personal property
                        lost in or stolen from the Parking Facility regardless
                        of whether such loss or theft occurs when the Parking
                        Facility or other areas therein are locked or otherwise
                        secured against entry or liable for any loss, injury or
                        damage to persons using the Parking Facility or
                        automobiles or other property therein, it being agreed
                        that the use of the Parking Facility and the 



                                       5
<PAGE>   12

                        parking spaces shall be at the sole risk of Sublessee
                        and its employees.

                c.      Sublessor and Landlord shall have the right from time to
                        time to promulgate reasonable rules and regulations
                        regarding the Parking Facility, the parking spaces and
                        the use thereof, including, but not limited to, rules
                        and regulations controlling the flow of traffic to and
                        from various parking areas, the angle and direction of
                        parking and the like, which rules and regulations and
                        any additions and amendments thereto Sublessor shall use
                        reasonable efforts to consistently apply to all users of
                        the Parking Facility. Sublessee shall comply with and
                        cause its employees to comply with all such rules and
                        regulations as well as all reasonable additions and
                        amendments thereto.

                d.      Except for emergency repairs, Sublessee and its
                        employees shall not perform any work on any automobiles
                        while located in the Parking Facility.

                e.      Landlord shall have the right to temporarily close the
                        Parking Facility or certain areas therein in order to
                        perform necessary repairs, maintenance and improvement
                        to the Parking Facility.

                f.      Except in connection with an approved assignment of the
                        Sublease or an approved subletting of all or a portion
                        of the Sublease Premises or any permitted transfer (as
                        hereinafter defined), in accordance with the terms
                        hereof, Sublessee shall not assign or sublease any of
                        the parking spaces. Sublessor shall have the right to
                        terminate this parking agreement with respect to any
                        parking spaces that Sublessee desires to sublet or
                        assign in violation of the foregoing sentence.

                g.      Landlord may elect to provide parking cards or keys to
                        control access to the Parking Facility. In such event,
                        Landlord shall provide Tenant with one card or key for
                        each parking space that Sublessee is leasing hereunder,
                        provided that Landlord shall have the right to require
                        Sublessee or its employees to place a reasonable deposit
                        on such access cards or keys and to pay a reasonable fee
                        for any lost or damaged cards or keys. Sublessee, at its
                        sole cost and expense, may obtain extra cards and keys
                        from Sublessor.

                h.      Sublessee shall pay to Sublessor, without any set-off or
                        deduction, all payments of Parking Rent in advance on or
                        before the first day of each calendar month during the
                        Term of this Sublease.

         2.6 Security Deposit. Sublessee concurrently with the execution of this
Sublease has deposited with Sublessor a deposit (the "Security Deposit") in the
amount of One Hundred Thirty-Seven Thousand Four Hundred Eighty-Nine and 00/100
DOLLARS 


                                       6
<PAGE>   13

($137,489.00) (constituting two (2) months of Yearly Fixed Rent), to be held by
Sublessor with interest as security for the faithful performance and observance
by Sublessee of the terms, conditions and provisions of this Sublease, including
without limitation the surrender of possession of the Sublease Premises to
Sublessor as herein provided. If the square footage of the Sublease Premises is
remeasured pursuant to Section 1.3 hereof, the Security Deposit shall be
recalculated to reflect an amount equal to two (2) months of Yearly Fixed Rent.
After such remeasurement, if the Security Deposit is greater than two (2) months
of Yearly Fixed Rent, any such excess shall be applied to Sublessee's next
payments of Yearly Fixed Rent due hereunder. After such remeasurement, if the
Security Deposit is less than two (2) months of Yearly Fixed Rent, any such
deficiency shall be paid by Sublessee as additional rent within thirty (30) days
after the execution of the Certificate attached hereto as Exhibit E. It is
agreed that in the event Sublessee defaults in respect of any of the terms,
provisions and conditions of this Sublease, including, but not limited to, the
payment of Yearly Fixed Rent, Parking Rent, Additional Rent, or any other
additional rent, which default continues after the giving of applicable notice
and the expiration of the applicable grace period set forth herein, Sublessor
may apply or retain the whole or any part of the Security Deposit to the extent
required for the payment of any Yearly Fixed Rent, Parking Rent and Additional
Rent or any other sum as to which Sublessee is in default, which default
continues after the giving of applicable notice and the expiration of the
applicable grace period set forth herein, or for any sum which Sublessor may
expend or may be required to expend by reason of Sublessee's default, which
default continues after the giving of applicable notice and the expiration of
the applicable grace period set forth herein, in respect of any of the terms,
covenants and conditions of this Sublease, including but not limited to, any
damages or deficiency in the reletting of the Sublease Premises, whether such
damages or deficiency accrue or accrues before or after summary proceedings or
other reentry by Sublessor. The Security Deposit is not to be used or applied by
Sublessee as a substitute for rent due any month, but may be so applied by
Sublessor in accordance with the terms of this Section 2.6. The use, application
or retention of the Security Deposit, or any portion thereof, by Sublessor in
accordance with the terms of this Section 2.6 shall not prevent Sublessor from
exercising any other right or remedy provided by this Sublease or by law and
shall not operate as a limitation on any recovery to which Sublessor may
otherwise be entitled. If Sublessor applies or retains any part of the Security
Deposit in accordance with the terms of this Section 2.6, Sublessee, upon
written demand therefor by Sublessor, shall deposit cash with Sublessor in such
amount so that Sublessor shall have the full deposit on hand at all times during
the Term. If Sublessee shall fully and faithfully comply with all of the terms,
provisions, covenants and conditions of this Sublease, and provided there are no
uncured Events of Default hereunder, the balance of the Security Deposit
together with all interest and earnings thereon (which interest and earnings
shall be the amount which would have been earned had the Security Deposit been
invested throughout the Term in a long term CD), shall be returned to Sublessee
within thirty (30) days after the expiration of the third lease year. If the
Security Deposit is not returned to Sublessee in accordance with the foregoing
sentence, and provided there are no uncured events of default hereunder, which
default continues after the giving of applicable notice and the expiration of
the applicable grace period set forth herein, the balance of the Security
Deposit together with all interest and earnings thereon (which interest and
earnings shall be the amount which would have been earned had the Security
Deposit been invested throughout the Term in a long term 



                                       7
<PAGE>   14

CD), shall be returned to Sublessee within thirty (30) days after the
Termination Date and after delivery of the entire possession of the Sublease
Premises to Sublessor.

3.       CONSTRUCTION

         3.1 Initial Construction. Sublessor shall perform or cause Landlord to
perform the Base Building Work and the Sublease Improvements as described in,
and in accordance with the terms, provisions and conditions of, the Work Letter
Agreement attached hereto as Exhibit F (which Work Letter is hereby incorporated
herein and made a part hereof). Sublessor shall provide Sublessee with a tenant
allowance in the amount equal to the number of rentable square feet that
comprises the Sublease Premises times $75.00 (the "Tenant Allowance"). The
Tenant Allowance shall be used for those costs incurred in connection with the
Sublease Improvements and approved by Sublessor (the "Approved Sublessee Costs")
and shall be disbursed in accordance with the provisions of this Sublease. The
allocation of cost responsibility between the Base Building Work and the
Sublease Improvements shall also be set forth on Exhibit F-2 attached hereto.
Approved Sublessee Costs may include the following costs: the cost of preparing
the Complete Plans (as hereinafter defined) and the cost of constructing the
Sublease Improvements (as hereinafter defined), including architectural,
contracting and engineering fees associated with the Sublease Improvements.
Sublessor shall cooperate with, and shall use reasonable efforts to cause its
architect and engineer to cooperate with, Sublessee's architect and engineer in
connection with the preparation of Sublessee's construction drawings and
specifications for the Sublease Improvements. Sublessee shall cooperate with,
and shall use reasonable efforts to cause any architects, engineers and
construction consultants retained by Sublessee to cooperate with, Sublessor's
contractor, engineer, architects and subcontractors in connection with the
construction of the Sublease Improvements and Base Building Work (as hereinafter
defined). Sublessor shall deliver to Sublessee a set of the schematic design
documents (which documents shall show the core areas and structural elements of
the Building) for the Base Building Work (the "Base Building Plans") on or about
the fifth (5) day after the execution of this Sublease (the "Schematic Design
Delivery Date"). Sublessee shall use commercially reasonable efforts to deliver
to Sublessor for approval complete sets of construction drawings and
specifications for the Sublease Improvements (the "Complete Plans") prepared at
Sublessee's expense (subject to reimbursement out of the Tenant Allowance) by
(a) Sublessor's architect or an architect selected by Sublessee and approved by
Sublessor and (b) Sublessor's engineer or an engineer selected by Sublessee and
approved by Sublessor on a date which is sixty (60) days after the Schematic
Design Delivery Date, but in all cases Sublessee shall deliver the Complete
Plans to Sublessor on or before November 1, 1998 (the "Complete Plan Delivery
Date"), time being of the essence. The Complete Plans shall include but not be
limited to:

        a.      Furniture and Equipment Layout Plans

        b.      Dimensioned Partition Plans

        c.      Dimensioned Electrical and Telephone Outlet Plans

        d.      Reflected Ceiling Plans

        e.      Door and Hardware Schedules

        f.      Room Finish Schedules including wall, carpet and floor tile
                colors



                                       8
<PAGE>   15

        g.      Electrical, mechanical, plumbing and structural engineering
                plans 

        h.      All necessary construction details and specifications for work
                not otherwise specified.

Sublessor shall provide to Sublessee schematic design documents with respect to
the Base Building Work promptly after the same are completed, as set forth
above, as well as more detailed construction drawings and specifications (and
changes to any of the foregoing) after the same are prepared.

         Sublessor and Sublessee shall initial the Complete Plans after the same
have been submitted by Sublessee and approved by Sublessor as aforesaid.
Provided Sublessee shall have delivered the Complete Plans to Sublessor no later
than the Complete Plan Delivery Date, and in the event it should be determined
by the general contractor performing the Base Building Work (the "Sublessor's
Building Contractor") that a Sublease Improvement item would be less expensive
to install concurrently with the Base Building Work as opposed to after the
completion of the Base Building Work, and that portion of the Base Building Work
has not been commenced and/or completed, Sublessor shall use reasonable efforts
to cause such Sublease Improvement to be made concurrently with the Base
Building Work and the cost thereof shall be deducted from the Tenant Improvement
Allowance.

         Any remaining Tenant Allowance, after all items for which the Tenant
Allowance was intended for have been paid in full, and provided Sublessee is not
in default hereunder beyond applicable notice and cure periods provided for
herein, may be used by Sublessee as follows: (i) as a rent credit; (ii) to pay
for moving expenses; and (iii) to purchase fixtures and fixed equipment for the
Sublease Premises which shall stay with the Premises at the end of the Term.
Such remaining Tenant Allowance shall be paid to (a) Sublessee or (b)
Sublessee's vendor(s) as directed in writing by Sublessee, within thirty (30)
days after Sublessor's receipt of invoices (marked paid) and supporting
documentation for such invoices.

         All of Sublessee's construction, installation of furnishings and
equipment, and later changes or additions to the Complete Plans shall be
reasonably coordinated with any work being performed by Sublessor in such manner
as to maintain harmonious labor relations and not to damage the Building or the
Lot or to interfere unreasonably with Building operations. Except for (i) the
installation of furnishings and equipment which may be installed by various
vendors, which vendors may be selected by Sublessee without approval by
Sublessor provided Sublessee delivers to Sublessor written notice prior to the
commencement of any such installation work specifying the name of such vendors,
and (ii) the installation of telephone outlets which must be performed by the
telecommunications department of Boston University Medical Center, all at
Sublessee's expense, all work described in the Complete Plans (the "Sublease
Improvements") shall subject to the provisions of the Work Letter be performed
by the Sublessor's Building Contractor, provided the markup and fees for profit,
overhead and general conditions are equal to or less than those paid for the
Base Building Work, unless the Sublessor elects to competitively bid the general
contract for the construction of the Sublease Improvements, and the Sublessor's
Building Contractor competitively bids the subcontracts. Sublessor shall select
the 



                                       9
<PAGE>   16

subcontractors based on cost, quality and availability, subject to Sublessee's
reasonable approval, which approval shall not be unreasonably withheld, delayed
or conditioned. In furtherance of the foregoing, Sublessee may reasonably
disapprove Sublessor's selection of any particular subcontractor if the cost of
the selected subcontractor is greater than 8% of the cost of the lowest bid.
Sublessor shall not impose any Sublessor profit, Sublessor overhead or Sublessor
supervision cost in connection with the construction of the Sublease
Improvements.

         3.1A. Approval and Removal. With respect to those consent and approval
rights of Sublessor set forth in Section 3.1 and 3.1A and Exhibit F hereof,
Sublessor shall not unreasonably withhold, delay or condition its consent or
approval so long as the Complete Plans, and/or the architect, engineer or other
applicable person or entity selected by Sublessee, are consistent with the
quality of the Building (including the Base Building Work), shall not delay the
construction of the Base Building Work and/or the Sublease Improvements, shall
not violate any applicable laws, shall maintain harmonious labor relations and
shall not interfere with building operations or construction. Notwithstanding
the foregoing, Sublessor shall not approve any construction, alterations, or
additions (whether such construction, alterations or additions occur prior to or
after the Term Commencement Date) requiring unusual expense to readapt the
Sublease Premises to office, research and development and laboratory use
consistent with that of other comparable buildings in Boston on the Termination
Date or increasing the cost of construction, insurance or taxes on the Building
or of Sublessor's services called for in this Sublease unless Sublessee first
gives assurances acceptable to Sublessor that such readaptation shall be made
prior to the Termination Date without expense to Sublessor and makes provisions
acceptable to Sublessor for payment of any such increased costs attributable to
such construction, alterations and additions. Except as otherwise provided
herein, all alterations and additions shall be part of the Building except such
items as by writing at the time of approval the parties agree either shall be
removed by Sublessee on termination of this Sublease, or shall be removed or
left at Sublessee's election.

         To the extent any furnitures, trade fixtures and equipment are paid out
of Sublessee's own funds (and not paid out of any portion of the Tenant
Allowance), Sublessee shall be entitled to remove such furnitures, trade
fixtures and equipment prior to the Termination Date in accordance with the
terms of this Sublease. With respect to any alteration or addition made to the
Sublease Premises after the Term Commencement Date, which alteration or addition
is made to replace, restore and/or substitute an improvement constituting a
portion of the Sublease Improvements on the Term Commencement Date (or any
replacement thereof), all such alterations and/or additions shall remain part of
the Building on the Termination Date unless otherwise agreed to in writing by
the parties hereto. If such alteration and/or addition is not any such
substitute, replacement or restoration, Sublessee shall be entitled to remove
such alteration or addition in accordance with the terms of this Sublease on or
prior to the Termination Date. To the extent that any building systems are
altered in order to accommodate any such alteration or addition, all such
building systems and improvements thereto shall remain the property of Sublessor
on the Termination Date.



                                       10
<PAGE>   17

         3.1B. Decommission. Sublessee hereby agrees to decommission the
Sublease Premises prior to the Termination Date without any expense to Sublessor
in accordance with all applicable laws.

         3.2 Preparation of Premises for Occupancy. Sublessor covenants and
agrees to use commercially reasonable efforts to cause the Sublease Premises to
be ready for occupancy on or about October 1, 1999, which date shall, however,
be extended for that period of time that Sublessor is actually delayed in
causing the Sublease Premises to be ready for occupancy or Base Building Work to
be completed due to Tenant Delays (as hereinafter defined) and Force Majeure
Delays (as hereinafter defined). The Sublease Premises shall be deemed ready for
occupancy on the date on which (a) the Sublease Improvements (i) are completed
in accordance with the Work Letter, (ii) are approved to the extent required by
law by the building department and (iii) are ready for occupancy as certified by
Sublessor's architect with the exception of minor items which can be completed
without material interference with Sublessee and other items which because of
the season or weather or the nature of the item are not practicable to do at the
time; (b) the Building systems and the emergency generator referenced in the
Work Letter Agreement (which shall be lawfully operational) are in good working
order to support the operation of the Sublease Premises; (c) a certificate of
occupancy (which may be temporary, conditional or otherwise) has been issued for
the Sublease Premises or the Main Premises or the Building, as the case may be,
and Landlord's certificate that any such certificates of occupancy delivered to
Sublessee permit Sublessee to use the Sublease Premises for the Permitted Uses
and (d) possession of the Sublease Premises shall be delivered to Sublessee for
its exclusive use and possession, broom clean and free of construction debris
and materials and any personal property that is not being leased hereunder (the
"Completion Date"). If Sublessor is unable to complete construction of the
Sublease Premises due to a Tenant Delay and/or Force Majeure Delay, then the
Sublease Premises shall be deemed ready for occupancy on the date on which they
are actually made available in accordance with the provisions of (a) - (d) above
to Sublessee and Sublessee shall not be entitled to any damages as set forth
below.

         To the extent that any certificate of occupancy delivered in connection
with the Sublease Premises is conditional or temporary in nature, Sublessor
agrees to obtain a permanent certificate of occupancy for the Building or the
Sublease Premises, as the case may be, with all reasonable due diligence and in
all events prior to the expiration of the temporary or conditional certificate
of occupancy. During the Term, Sublessor will maintain any certificates of
occupancy as they relate to the Common Areas of the Main Premises and Sublessee
agrees to maintain any certificates of occupancy as they relate to the Sublease
Premises.

         3.2A Delay in Term Commencement Date. In the event that the Term
Commencement Date occurs later than October 1, 1999, specifically excluding any
delays which are Tenant Delays or Force Majeure Delays, Sublessor shall pay to
Sublessee as liquidated damages (in lieu of all other damages available to
Sublessee) $20,000 for each full month that the Term Commencement Date is so
delayed or a pro-rata share of $20,000 for any portion of a month that the Term
Commencement Date is so delayed. The October 1, 1999 date shall be extended by a
period equal to the period of Tenant Delays and Force 




                                       11
<PAGE>   18

Majeure Delays. Sublessor and Sublessee have agreed that in the event that the
Term Commencement Date is delayed beyond October 1, 1999, specifically excluding
any delays which are Tenant Delays or Force Majeure Delays, the actual damages
sustained by Sublessee would be uncertain in amount and difficult, if not
impossible, to ascertain, with precision and that the foregoing liquidated
damages are a fair and reasonable amount to be retained by Sublessee in
connection with the delay in the Term Commencement Date. The foregoing remedy
shall be Sublessee's sole and exclusive remedy under this Sublease, at law and
in equity, for a delay in the Term Commencement Date beyond October 1, 1999 on
the terms and conditions set forth above. Notwithstanding anything to the
contrary contained in Section 21 of the Sublease, the obligations of Sublessor
set forth in this Section 3.2A shall be recourse in an amount not to exceed
$250,000.00 plus all reasonable attorneys' fees incurred by Sublessee in any
enforcement action (provided such action is decided in Sublessee's favor) to
collect any amounts due and owing Sublessee under this Section 3.2A.

         3.2B Delay in Foundation Date. In the event that Sublessor determines
in good faith after execution and delivery of this Sublease, that Sublessor will
not start construction of the Building, that is, the pouring of footings for the
foundation on or before July 1, 1998, for any reason other than Tenant Delays or
Force Majeure Delays, Sublessor shall notify Sublessee of such determination and
Sublessee shall have the right to terminate this Sublease within seven (7)
business days of receipt by Sublessee of Sublessor's notification. The July 1,
1998 date shall be extended by a day for each day of Tenant Delays and Force
Majeure Delays. If Sublessee fails to notify and deliver to Sublessor in writing
(the "Sublessee's Termination Notice") notice of its election to terminate this
Sublease within such seven (7) business day period, Sublessee shall have waived
any further rights to terminate this Sublease or any rights to liquidated
damages in accordance with the provisions of this Section 3.2B. If Sublessee
elects to terminate this Sublease, provided Sublessee is not in default
hereunder beyond applicable notice and cure periods provided for herein and
provided Sublessee notifies Sublessor of its election to terminate in accordance
with the strict provisions of this Sublease, Sublessor shall pay to Sublessee
within thirty (30) business days after Sublessor receives the Sublessee's
Termination Notice, an amount equal to $250,000 as liquidated damages and this
Sublease shall terminate upon Sublessor's receipt of Sublessee's Termination
Notice except for those provisions which expressly survive the termination.
Sublessor and Sublessee have agreed that in the event that Sublessor determines
in good faith that the commencement of construction will not occur on or before
July 1, 1998, for any reason other than Tenant Delays or Force Majeure Delays,
the actual damages sustained by Sublessee would be uncertain in amount and
difficult, if not impossible, to ascertain, with precision and that the
foregoing liquidated damages are a fair and reasonable amount to be retained by
Sublessee in connection with this delay in construction. The foregoing remedy
shall be Sublessee's sole and exclusive remedy under this Sublease, at law and
in equity, if the commencement of construction will not occur on or before July
1, 1998 as specifically set forth above.

         Sublessor's payment obligations under Sections 3.2A and 3.2B shall
survive the termination of this Lease.



                                       12
<PAGE>   19

         3.3 General Provisions Applicable to Construction. All construction
work required or permitted by this Sublease, (including, without limitation, the
Work Letter Agreement), whether by Sublessor, Landlord or Sublessee, shall be
done in a good and workmanlike manner and in compliance with all applicable laws
and all lawful ordinances, regulations and orders of governmental authority and
insurers of the Building. Either party may inspect the work of the other at
reasonable times and promptly shall give notice of observed defects. Sublessor's
obligations under Section 3.1 shall be deemed to have been performed when
Sublessee commences to occupy any portion of the Sublease Premises for the
Permitted Uses except for items which are incomplete or do not conform with the
requirements of Section 3.1 and as to which Sublessee shall in either case have
given written notice to Sublessor within sixty (60) days after the Term
Commencement Date. Failure to so notify Sublessor shall be deemed a waiver by
Sublessee of any incomplete or nonconforming items by Sublessor.

         3.4 Force Majeure Delays. "Force Majeure Delays" shall mean any of the
following events: lack of, unusual scarcity or inability to obtain labor,
supplies and materials (other than because of a lack of funds); strikes; riots;
acts of God; weather and storm conditions; war; state of emergency; casualty;
eminent domain; governmental laws, regulations or restrictions of any agencies,
boards, authorities or the like; delays by any such agencies, boards,
authorities, or the like in granting, issuing or delivering any permits,
licenses, variances, approvals, consents or the like regarding the Sublease
Premises, the Building and the Lot; any cause described in Section 21 hereof;
and any other cause whatsoever that is beyond the reasonable control of
Sublessor or Landlord (other than because of lack of funds). Except as
specifically provided herein to the contrary, whenever a period of time is
prescribed in this Sublease (including without limitation, the Work Letter
Agreement) for the taking of any action by Sublessor, Sublessor shall not be
liable or responsible for, and there shall be excluded from the computation of
such period of time, any delays due to events of Force Majeure.

         3.5 Tenant Delays. Whenever a period of time is herein prescribed for
the taking of any action by Sublessor during the period commencing on the
execution date of this Sublease and ending on the Term Commencement Date,
Sublessor shall not be responsible for or liable, and there shall be excluded
from the computation of such period of time any of the following delays (a
"Tenant Delay"):

                a.      Sublessee's failure to furnish information or deliver
                        plans in accordance with this Sublease including Section
                        3.1 hereof or the Work Letter Agreement or to respond to
                        any request by Sublessor for any approval or information
                        within any time period prescribed, or if no time period
                        is prescribed, then within five (5) business days of
                        such written request; or

                b.      Sublessee's insistence on materials, finishes or
                        installations that have long lead times after having
                        first been informed by Sublessor that such materials,
                        finishes or installations will cause a delay; or



                                       13
<PAGE>   20

                c.      Changes in any plans and specifications requested by
                        Sublessee that delay Sublessor in the completion of the
                        Sublease Improvements or Base Building Work; or

                d.      The performance or nonperformance by a person or entity
                        employed by Sublessee in the completion of any work in
                        the Sublease Premises (all such work and such persons or
                        entities being subject to the prior approval of
                        Sublessor); or

                e.      Any request by Sublessee for changes to the Sublease
                        Improvements that actually delay Sublessor in the
                        completion of any of the Sublease Improvements or Base
                        Building Work; or

                f.      Any breach or default by Sublessee in the performance of
                        Sublessee's obligations under this Sublease that delays
                        Sublessor in the completion of any of the Sublease
                        Improvements or Base Building Work; or

                g.      Any delay resulting from Sublessee's access to the
                        Sublease Premises or having taken possession of the
                        Sublease Premises for any reason prior to substantial
                        completion of the Sublease Improvements or Base Building
                        Work. For purposes of determining the Term Commencement
                        Date, the date of Substantial Completion shall be
                        determined in accordance with Section 3.2.

                All of the forgoing a. through g. being a "Tenant Delay" for
        purposes of this Sublease.

         3.6 Access During Construction. During the construction of the Sublease
Improvements, Sublessee shall have the right to enter the Sublease Premises for
the purpose of inspecting the Sublease Improvements and thirty (30) days prior
to the Term Commencement Date for the installation of Sublessee's equipment and
trade fixtures. Notwithstanding the foregoing, any such inspection or
installation shall be performed only upon reasonable prior notice to Sublessor
and at reasonable times designated by Sublessor so as not to interfere with the
performance of the Base Building Work and Sublease Improvements. If Sublessee's
access shall interfere with the timely completion of the Base Building Work
and/or Sublease Improvements, Sublessee's right to access shall be terminated
immediately.

         3.7 Signage. Sublessor shall provide, at Sublessor's sole cost and
expense, or shall cause Landlord, at Landlord's sole cost and expense, to
provide (a) a standard building directory in the lobby of the Building listing
Sublessee as a tenant and (b) Sublessee suite identification on the exterior of
the Sublease Premises using building standard graphics identifying the suite
number of Sublessee. Sublessee, at its sole cost and expense, shall have the
right to install (1) building eyebrow signage on the exterior of the Building on
the Albany Street side of the Building in a location designated by Sublessor or
Landlord, the 



                                       14
<PAGE>   21

location of which shall conform to the sign standards enacted from time to time
for the Building ("Building Eyebrow Signage"), upon prior reasonable written
notice to Sublessor and in a manner so as not to interfere with the rights of
other tenants in the Building, (2) custom signage identifying Sublessee on any
full floors leased by Sublessee, provided that such signage is not visible from
outside the Building (it being agreed that the ground floor being leased by
Sublessee hereunder constitutes a full floor for purposes of this clause (2))
and (3) if a monument is built by Landlord, written identification on monument
signage. The cost for (1), (2) and (3) may be funded out of the Tenant
Improvement Allowance. Notwithstanding the foregoing, all signage installed by
Sublessee shall be compatible with all design and architectural guidelines
established for the Building, conform to the sign requirements for the Building
as enacted from time to time for the Building, conform to all laws, ordinances
and regulations including without limitation, all zoning laws and any
requirements of any historic and/or Boston agencies regarding the same and shall
be subject to the reasonable review and prior written approval of Sublessor. It
shall be Sublessee's sole responsibility to apply for and obtain all permits,
licenses and governmental approvals for the construction of any Building Eyebrow
Signage and any custom signage on any full floors leased by Sublessee (Building
Eyebrow Signage and custom signage being referred to collectively as the
"Sublessee Signage"). Sublessee agrees to maintain all necessary licenses and
permits for the Sublessee Signage and to maintain the Sublessee Signage in good
order, condition and repair at Sublessee's sole cost and expense, it being
understood that Landlord and Sublessor shall have absolutely no responsibility
for Sublessee Signage. Sublessee shall defend, indemnify and save Landlord and
Sublessor harmless in connection with the Sublessee Signage as provided for in
Section 11.3 herein. Sublessor, at no cost and expense to Sublessor, shall
cooperate (and shall cause Landlord to cooperate) with Sublessee in obtaining
the necessary permits, licenses and governmental approvals for Sublessee
Signage. Notwithstanding anything to the contrary contained herein, Sublessee
shall be free to erect any signage it desires within the Sublease Premises
provided it is not visible outside of the Sublease Premises in which latter
case, such signage shall require the approval of Sublessor. Sublessor may at its
option require the Sublessee at or prior to the expiration of the Term to remove
all Sublessee Signage and to repair any damage caused by such removal.

4.       USE OF THE SUBLEASE PREMISES

         4.1 Permitted Uses. Sublessee shall continuously (as further described)
during the Term of this Sublease occupy and use the Sublease Premises solely for
office, research and development, vivarium, fabrication, assembly and
distribution uses in connection with the production by Sublessee of biochemical,
immunological, molecular biology and other life sciences products subject to
Section 4.2(iii) hereof and for no other purpose. As further clarification to
the preceding sentence, the term "continuously" shall mean continuous use of the
Sublease Premises by the Sublessee or other occupants permitted under this
Sublease for the Permitted Uses Monday through Friday from 9:00 A.M. to 5:00
P.M., subject to those normal periods of non-occupancy for vacations and federal
and state holidays and subject further to non-occupancy of certain portions of
the Sublease Premises due to the space needs of Sublessee from time to time, it
being understood and agreed by Sublessee that it shall during the Term of the
Sublease be responsible for the maintenance and operation 



                                       15
<PAGE>   22

responsibilities for the entire Sublease Premises set forth herein as
Sublessee's responsibilities and for conveying to the general public the image
and appearance of continued presence and full occupancy of the entire Sublease
Premises. Service and utility areas (whether or not a part of the Sublease
Premises) shall be used only for the particular purpose for which they were
designated. It shall be Sublessee's full responsibility to obtain all permits
and licenses to conduct the foregoing uses in the Sublessee Premises
specifically excluding the certificate of occupancy (described in Section
3.2(c)), and any other certificates of occupancy (permanent or otherwise) for
the Building to the extent required by law. If Sublessee shall change its use
(with the permission of Sublessor) or increase the number of rodents (with the
permission of Sublessor) above 5,000 rodents, Sublessee shall be responsible for
obtaining for any certificate(s) of occupancy required as a result of the same.

         4.2 Prohibited Uses. Sublessee shall not use, or suffer or permit the
use of, or suffer or permit anything to be done in the Sublease Premises or the
Building (i) which would violate any of the covenants, agreements, terms,
provisions and conditions of this Sublease, (ii) for any unlawful purposes or in
any unlawful manner, or (iii) which, in the reasonable judgment of Sublessor or
Landlord shall in any material respect (a) impair or tend to impair the
appearance or reputation of the Building in such a manner so as to detract from
the quality of conditions at the Building as compared with other comparable
buildings in the Boston University Medical Campus, (b) impair or interfere with
any of the Building services or the proper and economic heating, cleaning, air
conditioning or other servicing of the Building, or (c) occasion discomfort,
inconvenience or annoyance to any of the other tenants or occupants of the
Building, whether through the transmission of noise or noxious or offensive
odors or otherwise. Without limiting the generality of the foregoing, no food
(except in connection with customary office vending machines, coffee service
facilities and lunch room facilities set forth on the Complete Plans or other
plans approved by Sublessor, provided such machines and facilities are used for
and by occupants of the Sublease Premises only and their guests and further
provided Sublessee pays any resulting increased costs pursuant to Section 13.8
and the other applicable provisions of this Sublease) shall be prepared or
served for public or commercial consumption on or about the Sublease Premises;
no intoxicating liquors or alcoholic beverages shall be sold or otherwise served
to the general public on or about the Sublease Premises; no lottery tickets
(even where the sale of such tickets is not illegal) shall be sold and no
gambling, betting or wagering shall otherwise be permitted on or about the
Sublease Premises; no loitering shall be permitted on or about the Sublease
Premises; and no loading or unloading of supplies or other material to or from
the Sublease Premises shall be permitted on the Lot except during such hours as
the Building is customarily open for business. The Sublease Premises shall be
maintained by Sublessee in a sanitary condition, kept free from noxious or
offensive odors (including but not limited to rodent or other laboratory animal
odors) and kept free from vermin and, except as provided herein below, rodents.

         Notwithstanding anything contained herein to the contrary, Sublessee
may maintain not more than a maximum number of five thousand (5,000) rodents in
the Sublease Premises at any one time during the Term provided (i) Sublessee
delivers to Sublessor within thirty (30) days after the Term Commencement Date a
complete report of the number of rodents 



                                       16
<PAGE>   23

and location of where the rodents will be housed, together with copies of all
necessary licenses and permits, (ii) Sublessee shall comply during the Term with
all applicable laws in connection with maintaining said rodents, including
without limitation the laws of the US Department of Agriculture, (iii) Sublessee
shall obtain all licenses and permits required to house such rodents (other then
certificates of occupancy), (iv) Sublessee shall comply with all applicable
density requirements regarding the housing of such rodents as required by
applicable law, and (v) Sublessee shall obtain such insurance as may be
reasonably required due to the laboratory use of rodents in the Sublease
Premises. Sublessee shall comply with the provisions of the foregoing sentence
at its sole cost and expense. Notwithstanding the foregoing, and provided
Sublessee is not in default hereunder beyond notice and applicable cure periods
provided for herein, Sublessee may maintain additional laboratory animals in the
Sublease Premises only with Sublessor's prior written consent and approval and
in compliance with all applicable laws (including without limitation laws of the
US Department of Agriculture), the terms and conditions of this Sublease, and
the reasonable Laboratory Animals Specifications promulgated for the Building
from time to time by Landlord and Sublessor. Notwithstanding anything contained
herein to the contrary, Sublessee shall in good faith consider locating any
rodents or other laboratory animals (approved in accordance with the terms of
the Sublease) on the second floor of the Sublease Premises; provided that
Sublessee shall not have any obligation so to locate any such animals.

         Sublessee shall provide Sublessor with a list of the laboratory animals
(which number of animals may not increase and which type of animals may not
change without the prior written approval of Sublessor) and shall update said
list from time to time as may be requested by Sublessor (but not more than three
times per lease year unless any further updates are required by applicable law),
within twenty (20) days after such request.

         Sublessee shall be responsible for the proper handling and disposal of
all its trash, rubbish and other wastes, and for compliance with all local,
state and federal laws applicable to the storage and disposal of any such
wastes. Sublessee shall also provide cleaning services to the Sublease Premises
according to cleaning standards generally prevailing from time to time in
comparable office and research and development buildings in the City of Boston
(but specifically taking into consideration the housing of rodents) and in
accordance with any cleaning specifications promulgated from time to time by
Landlord and Sublessor conforming to such standards.

         4.3 Licenses and Permits. If any governmental license or permit
(specifically excluding the certificate of occupancy described in Section
3.2(c)) shall be required for the proper and lawful conduct of Sublessee's
business, and if the failure to secure such license or permit would in any way
affect Landlord or Sublessor, Sublessee, at Sublessee's expense, shall duly
procure and thereafter maintain such license or permit and submit the same to
inspection by Landlord or Sublessor. Sublessee, at Sublessee's expense, shall at
all times comply with the terms and conditions of each such license or permit.

         4.4 Equipment. Sublessee shall at all times install, maintain and
operate all equipment used or located in the Sublease Premises in accordance
with manufacturers' 



                                       17
<PAGE>   24

specifications and warranties, to the extent applicable. To the extent allowed
by law and to the extent allowed by said manufacturers, Sublessor shall assign
or cause Landlord to assign to Sublessee any manufacturers' warranties which
Sublessor or Landlord has in its possession as of the Term Commencement Date for
any equipment serving exclusively the Sublease Premises.

         4.5 Access. Commencing on the Term Commencement Date, Sublessee shall
have access to the Building twenty-four (24) hours per day, 365/366 days per
year and during those hours that the Building is not accessible to the general
public, via a security card system provided by Landlord. Sublessee agrees to use
and comply with any security systems including the security card systems
employed by Landlord and Sublessor from time to time during the Term of this
Sublease. Sublessor shall provide or shall cause Landlord to provide a manned
security desk within the lobby of the Building comparable to that of other
buildings in the Boston University Medical Campus from 6:30 a.m. until 10:30
p.m. seven days per week, it being understood by Sublessee that the provision of
a security desk and security card systems are no warranty, representation or
guaranty by Landlord or Sublessor as to the safety or security of persons and
property within the Building, the Sublease Premises or the Building.
Notwithstanding the foregoing sentence, Sublessee shall be solely responsible
for the security of all persons and property within the Sublease Premises and
for access to the Sublease Premises including any security card system serving
the Sublease Premises.

         4.6 Extra Hazardous Use. Sublessee covenants and agrees that Sublessee
will not do or permit anything to be done in or upon the Sublease Premises, or
bring in anything or keep anything therein, which would invalidate or be in
conflict with any insurance coverage maintained by or for the Sublessor with
respect to the Building as set forth in Section 11 hereof or which would
increase the rate of such insurance on the Sublease Premises or on the Building
above the standard rate applicable to the Sublease Premises or the Building; and
Sublessee further agrees that, in the event that the Sublessee shall do any of
the foregoing, Sublessee will, at Sublessor's election, cease such activity or
promptly pay to Sublessor, on demand, any such increase resulting therefrom,
which shall be due and payable as additional rent hereunder.

         Sublessee shall not cause or permit any Hazardous Materials (as
hereinafter defined) to be used, generated, stored or disposed of on, under or
about, or transported to or from, the Sublease Premises or the Building
(collectively, "Hazardous Materials Activities") without first submitting to
Sublessor at least forty (40) days prior to the Term Commencement Date, a
complete and comprehensive Hazardous Materials Inventory Statement listing the
types and quantities of all Hazardous Materials to be used, generated, stored or
disposed of, on, above, under, about, or transported to or from the Sublease
Premises or the Building (the "Inventory"). In addition, at least thirty (30)
days prior to the commencement of each subsequent lease year during the Term of
this Sublease, Sublessee shall update such Inventory by adding and/or deleting
Hazardous Materials from said Inventory, as appropriate, and deliver said
updated Inventory indicating all Hazardous Materials then being used or to be
used, generated, stored or disposed of, on, above, under, about or transported
to or from the Sublease Premises or the Building. Sublessor shall have the right



                                       18
<PAGE>   25

to disapprove of any Hazardous Materials listed on such Inventories if Sublessor
in its reasonable business judgment is of the opinion that the use, generation,
storage or disposal or transportation of such Hazardous Materials will violate
any applicable Regulations or will jeopardize human health, safety or the
environment, which judgment of Sublessor shall be supported by Boston
University's Office of Environmental Health and Safety. If Sublessor consents to
any such Hazardous Materials Activities, the Sublessee shall conduct them in
strict compliance (at Sublessee's expense) with all applicable Regulations (as
hereinafter defined) and using all necessary and appropriate precautions to
prevent any spill, discharge, release or exposure to persons or property.
Sublessor shall not be liable to Sublessee for any loss, cost, expense, claims,
damage or liability arising out of any Hazardous Materials Activities by
Sublessee, Sublessee's employees, agents, contractors, licensees, customers or
invitees, whether or not consented to by Sublessor. Sublessee shall indemnify,
defend with experienced and competent counsel, and hold Sublessor harmless from
and against any and all loss, costs, expenses, claims, damages or liabilities
arising out of all Hazardous Materials Activities on the Sublease Premises by or
at the direction of the Sublessee, whether or not consented to by Sublessor
which obligation shall survive the termination of this Sublease. Sublessee shall
also provide Sublessor with a copy of any Hazardous Materials inventory
statement or similar document required by any applicable Regulations, and any
update filed in accordance with any applicable Regulations, and shall deliver
the same to Sublessor within thirty (30) days of said filing. If Sublessee's
activities violate any Regulations or cause a spill, discharge, release or
exposure to any persons or property in violation of applicable law, Sublessee
shall cease such activities immediately. Sublessee shall immediately notify
Sublessor both by telephone and in writing of any such spill, discharge, release
or exposure of Hazardous Materials or of any condition constituting an "imminent
hazard" under any Regulations. Sublessor and Sublessor's representatives and
employees may enter the Sublease Premises at any reasonable time during the Term
upon no less than twenty-four (24) hours' prior telephonic notice, accompanied
by a representative of the Sublessee if one is available (except in event of
emergency) to inspect the Sublessee's compliance herewith, and may disclose any
spill, discharge, release, or exposure or any violation of any Regulations to
any governmental agency with jurisdiction.

         Sublessee shall undertake no environmental testing of the Lot itself
without Sublessor's consent, which consent may be withheld in the Sublessor's
sole discretion, unless such testing is required by applicable law, in which
case Sublessee shall give Sublessor prompt written notice of any applicable law
or order requiring Sublessee to undertake environmental testing of the Lot, in
which case, to the extent permitted under applicable law, Sublessor may always
elect to undertake such environmental testing at Sublessee's cost and expense
but for the benefit of Sublessee. Notwithstanding the foregoing sentence,
Sublessee may undertake any environmental testing within the Sublease Premises
as is required by all applicable laws provided Sublessee provides prompt
reasonable advance notice to Sublessor of such testing and agrees to defend,
indemnify and save Landlord and Sublessor harmless in connection with any such
testing to the extent provided for in Section 19 herein. The provisions of this
Section 4.6 shall survive the expiration or earlier termination of this
Sublease.



                                       19
<PAGE>   26

5.       RENT; UTILITIES

         5.1 Yearly Fixed Rent. Commencing with the Rent Commencement Date (as
hereinafter defined), Sublessee shall pay to Sublessor, without any set-off or
deduction (except as otherwise expressly provided in this Sublease), at
Sublessor's office, or to such other person or at such other place as Sublessor
may designate by notice to Sublessee, the Yearly Fixed Rent. The Yearly Fixed
Rent shall be paid in equal monthly installments in advance on or before the
first day of each calendar month during the Term of this Sublease and shall be
apportioned for any fraction of a month occurring during the Term in which the
Rent Commencement Date or the last day of the Term of this Sublease may fall.
For purposes of this Sublease, "Yearly Fixed Rent" shall equal $29.00 per
rentable square foot per annum for the first five lease years of the Term and
$34.00 per rentable square foot per annum for the sixth through tenth lease
years of the Term. For purposes of this Sublease, the first lease year shall
include the first twelve (12) calendar months of the Term, together with any
partial month at the beginning of the Term. Successive lease years shall be
comprised of succeeding periods of twelve (12) calendar months. Simultaneously
with the execution of this Sublease, Sublessee shall deliver to Sublessor the
first monthly installment of Yearly Fixed Rent. The "Rent Commencement Date"
shall be the later of (a) October 1, 1999 or (b) the Term Commencement Date.

         5.2 Additional Rent. Commencing with the Rent Commencement Date,
Sublessee shall pay to Sublessor without any set-off or deduction (except as
otherwise expressly provided in this Sublease), at Sublessor's office, or to
such other person or at such other place as Sublessor may designate by notice to
Sublessee, the Additional Rent (as defined below). The Additional Rent shall be
paid in equal monthly installments in advance on or before the first day of each
calendar month during the Term of this Sublease based upon a statement of
Sublessor's good faith estimate of Additional Rent in respect of Operating
Expenses provided by Sublessor to Sublessee at least thirty (30) days prior to
the first day of each Building fiscal year (as hereinafter defined) (the
"Estimated Expense Statement"). Payments of Additional Rent shall be apportioned
for any fraction of a month occurring during the Term in which the Term
Commencement Date or the last day of the Term of the Sublease may fall.
Sublessor, in good faith, shall have the right to provide adjusted Estimated
Expense Statements during any Building fiscal year and in the event Sublessor
fails to provide an Estimated Expense Statement thirty (30) days prior to the
commencement of any given Building fiscal year, Sublessee shall continue to pay
Additional Rent based upon the immediately preceding Estimated Expense Statement
until such time as Sublessor provides Sublessee with a new Estimated Expense
Statement.

         Within six (6) months after the last day of each Building's fiscal year
during the Term of this Sublease, Sublessor shall furnish Sublessee with a
statement of actual Additional Rent for such Building fiscal year in respect of
Operating Expenses certified by an officer of Sublessor (the "Actual Expense
Statement"). In the event the Actual Expense Statement shows that there exists a
deficiency between the Additional Rent which was due by Sublessee and the actual
Additional Rent paid by Sublessee, Sublessee shall pay such deficiency to
Sublessor within thirty (30) days of receipt of such Actual Expense Statement.
In the event the Actual Expense Statement shows that an overpayment of
Additional Rent 



                                       20
<PAGE>   27

has been made by Sublessee then Sublessor shall credit the next installments of
Additional Rent due hereunder, or, in the event there is no such Additional Rent
due, Sublessor shall return such overpayment to Sublessee within thirty (30)
days of receipt of Sublessee's written notice requesting same.

         For purposes of this Sublease, "Operating Expenses" for any given
Building fiscal year shall equal the product of (a) Sublessee's Proportionate
Share (as defined in Section 2.3 hereof) times (b) all costs and expenses
incurred annually by Landlord and Sublessor in the operation and maintenance of
the Building and the Lot in accordance with generally accepted operational and
maintenance procedures consistent with the management of comparable office and
research/development buildings in the greater Boston area' that are commonly
utilized by Boston University in other buildings in the Boston University
Medical Campus, as determined in accordance with GAAP, including, without
limiting the generality of the foregoing, all such costs and expenses in
connection with (1) insurance, all insurance deductibles, license fees,
security, janitorial service, landscaping, and snow removal, (2) wages,
salaries, management fees, employee benefits, payroll taxes, onsite office
expenses, administrative and auditing expenses, and equipment and materials for
the operation, management, maintenance of the Building and Lot, (3) any capital
expenditures (amortized, with interest at a rate equal to the prime rate from
time to time (as published by The Wall Street Journal) plus one percent (1%),
over its estimated useful life according to GAAP) made by Landlord or Sublessor
for the purpose of reducing other operating expenses or complying with any
governmental requirement enacted after the Term Commencement Date and any
capital expenditures (amortized as set forth herein) of structural items (as
defined in Section 13.7B hereof) made to comply with any governmental
requirement enacted after the Term Commencement Date, (4) the furnishing of
heat, air conditioning, utilities, and any other service (specifically excluding
any service to the extent to which Sublessor or Landlord is entitled to special
reimbursement by individual tenants and specifically excluding electricity which
is separately metered or submetered and which Sublessee pays directly to the
public utility providing same or to Sublessor), (5) the furnishing of the
repairs and other services (excluding capital expenditures as defined pursuant
to GAAP except as set forth above), and (6) data processing charges reasonably
allocable to the Building.

         Notwithstanding anything to the contrary contained herein, the
following shall be excluded from Additional Rent: (1) wages, salaries, or other
compensation or benefits paid to any persons above the grade of Building manager
(or equivalent position); (2) debt service; (3) capital expenditures (except to
the extent expressly permitted under this Section 5.2)); (4) depreciation and
amortization (except to the extent expressly permitted under this Section 5.2);
(5) expenses of redecorating and renovating space for new or existing tenants or
for tenants renewing their leases; (6) legal and accounting fees relating to (A)
disputes with occupants of the Building, or (B) disputes with purchasers,
prospective purchasers, mortgages or prospective mortgagees, or (C) negotiations
of leases, contracts of sale or mortgages; (7) brokerage commissions; (8) any
rent under any ground or underlying lease (including, without limitation, the
Main Lease); (9) any fines or penalties incurred due to violations by Landlord,
Sublessor or any tenant or other occupant of the Building of any law; (10) any
amount incurred to a company or other entity affiliated with Landlord or



                                       21
<PAGE>   28

Sublessor to the extent the same exceeds the amount which would have been
incurred on a fair market basis in the absence of such affiliation; (11) any
interest, fines or penalties incurred resulting from late payment by Landlord or
Sublessor of any operating expense; (12) costs incurred in connection with the
removal, encapsulation or other treatment of any Hazardous Materials (as defined
below) not caused by Sublessee (except to the extent expressly permitted under
this Section 5.2); (13) any amounts incurred for repairs or other work
occasioned by fire, windstorm, or other casualty (only to the extent Sublessor
is reimbursed by insurance or would have been reimbursed by insurance had
Sublessor maintained the insurance it is required to maintain under this
Sublease) and specifically excluding the amount of any deductibles); (14) any
costs incurred for cleaning or janitorial services, utilities or other services
if provided to one or more occupants of the Building but not required by this
Sublease to be provided to Sublessee without separate charge; and (15) costs in
respect of structural items (except as expressly set forth above).

         Provided Sublessee is not in default hereunder beyond any applicable
notice and grace period, Sublessee shall have the right to inspect, copy and
audit those portions of Sublessor's and Landlord's book and records with respect
to Operating Expenses. Sublessee shall give Sublessor notice of the exercise of
its inspection and audit right hereunder with respect to any immediately
preceding Building fiscal year no later than one hundred eighty (180) days after
receipt from Sublessor of the Actual Expense Statement for such Building fiscal
year. Sublessor shall, within sixty (60) days of receipt of Sublessee's written
request hereunder, make available or shall cause Landlord to make available such
books and records. If Sublessee disputes the correctness of any Actual Expense
Statement and Sublessor and Sublessee cannot resolve such dispute within thirty
(30) days after such dispute arises, then either Sublessor or Sublessee may
require that such dispute be resolved by a certified public accounting firm
designated by the American Arbitration Association (or any successor thereto),
whose decision shall be binding on Sublessee and Sublessor and whose cost shall
be paid by the nonprevailing party. If the dispute shall be determined in
Sublessee's favor, then Sublessor, within thirty (30) days after the
determination, shall refund to Sublessee the amount of Sublessee's overpayment
of Operating Expenses. The provisions of this paragraph shall survive the
expiration or earlier termination of this Sublease.

         Notwithstanding anything to the contrary contained herein, Sublessee's
Proportionate Share of Additional Rent attributable to the property management
fee for the Building fiscal year or any portion thereof shall not exceed $.50
per rentable square foot of the Sublease Premises for the first Building fiscal
year of the Term. In any Building fiscal year after the first Building fiscal
year, Sublessee's Proportionate Share of Additional Rent attributable to the
property management fee shall not increase by more than 3% in any given Building
fiscal year. Sublessor covenants to provide or shall cause Landlord to provide
property management services to the Building consistent in quality with property
management services at comparable properties in the same geographic area of
Boston in which the Building is located. "Building fiscal year" shall mean each
twelve month period commencing on July 1 and ending on June 30, which twelve
(12) month period may be amended from time to time by Sublessor. "First Building
fiscal year" shall mean the period commencing July 1, 1999 and ending on June
30, 2000.



                                       22
<PAGE>   29

         5.2A Tax and Tax Fund Payments. Commencing with the Term Commencement
Date, Sublessee shall pay to Sublessor as additional rent Sublessee's
proportionate share (as may be adjusted as set forth below) of all real estate
taxes (including, without limitation, all betterment assessments, amortized over
the longest period permitted by law, all reasonable tax abatement costs, all
charges in lieu of such taxes and any tax on any fixture installed in the
Building (including the Sublease Premises) even if taxed as personal property)
imposed against the Building and the Lot, prorated with respect to any portion
of a calendar year in which the Term of this Sublease begins or ends
("Additional Rent for Taxes"). The term "real estate taxes" for the purposes
hereof shall include all gross receipts or similar taxes, if any, imposed or
levied upon, assessed against or measured by any Yearly Fixed Rent, Additional
Rent or other sum payable hereunder, and all sales, value added, use and similar
taxes, if any, at any time levied, assessed or payable on account of the leasing
or use of the Sublease Premises; provided, however, that nothing contained in
this Sublease shall require Sublessee to pay any franchise, corporate, estate,
inheritance, succession, capital levy or transfer tax of Sublessor or Landlord,
or any income, profits or revenue, gift or capital stock tax or charge upon the
Yearly Fixed Rent and Additional Rent payable by Sublessee under this Sublease,
or any interest or penalties or any real estate taxes (provided Sublessee is not
in default in its payments of Yearly Fixed Rent and Additional Rent hereunder).

         Notwithstanding anything to the contrary set forth herein, Sublessee's
proportionate share of all real estates taxes imposed against the Building and
the Lot shall be recalculated from time to time during the Term of this Sublease
to the extent Sublessor is successful in obtaining tax exempt status for the
Property or any portion thereof and/or enters into a so called pilot agreement
with the City of Boston with respect to the Property if and only if such tax
exemption or pilot agreement includes the Sublease Premises. "Pilot agreement"
shall mean any agreement entered into by and between Sublessor (or Landlord) and
the City of Boston for payment in lieu of taxes due to the Sublessor's (or
Landlord's) not-for-profit status. Any payments due under any pilot agreements
shall be referred to as "pilot payments". Any recalculation of real estate taxes
shall be as follows:

         The sum of:

         (a) For those uses of the Sublease Premises or portions thereof which
are attributable to Sublessee's tax exempt or not-for-profit uses, Sublessee's
proportionate share of real estate taxes shall be equal to the product of (i)
any pilot payments for the Building or any portion thereof times (ii) the
fraction, the numerator of which shall be the number of rentable square feet of
Sublease Premises used for tax exempt or not-for-profit uses and the denominator
of which shall be the number of rentable square feet in the Building which are
the subject of the pilot agreement, and

         (b) For retail or for profit uses of the Sublease Premises, Sublessee's
proportionate share of real estate taxes shall be equal to the product of (i)
tax bill for the portion of the Building used for retail or for-profit uses
times (ii) the fraction, the numerator of which shall be the number of rentable
square feet of Sublease Premises used for retail or for-profit uses and the
denominator of which shall be the number of rentable square feet in 



                                       23
<PAGE>   30

the Building used for retail or for-profit uses. Sublessor and Sublessee
acknowledge that the proportionate share of real estate taxes due from Sublessee
from time to time during the Term of the Sublease may be recalculated as set
forth in the preceding sentences.

         Notwithstanding anything to the contrary contained herein, if different
tax treatment is accorded by the taxing authorities with respect to vacant space
in the Sublease Premises or different tax treatment is accorded by the taxing
authorities with respect to office, retail or research and redevelopment uses in
the Building or the Main Premises, as the case may be, Sublessee's proportionate
share of real estate taxes shall be recalculated from time to time during the
Term to reflect such different tax treatment and in all events Sublessee shall
be responsible for all real estate taxes attributable to the Sublease Premises.

         To the extent that Sublessor or Landlord receives a refund or reduction
with respect to real estate taxes payable by Sublessee under this Sublease after
such refund or reduction is actually received by Sublessor, Sublessor, after
deducting all reasonable expenses associated therewith, shall pass on to
Sublessee its share of such refund or reduction. The forgoing sentence shall
survive the expiration or sooner termination of this Sublease.

         Sublessee shall, with each monthly installment of Yearly Fixed Rent,
make tax fund payments to Sublessor in the amount of one twelfth (1/12) of the
estimated tax due. "Tax fund payments", with respect to any given fiscal year,
refer to such payments as Sublessor shall reasonably determine to be sufficient
to provide in the aggregate a fund adequate to pay all payments required from
Sublessee pursuant to Section 5.2A for such fiscal year when they become due and
payable. The term "fiscal year" shall mean the twelve month period commencing on
July 1 and ending on June 30th or such twelve month period designated by the
taxing authority for the City of Boston as a fiscal year from time to time.
Sublessor, within thirty days after Sublessee's request for a copy of the actual
tax bill (the "Tax Bill"), shall furnish Sublessee with a copy of the Tax Bill
for each fiscal year during the Term of this Sublease. Tax fund payments shall
be paid in equal monthly installments in advance on or before the first day of
each calendar month during the Term of the Sublease based upon a statement of
Sublessor's good faith estimate of Additional Rent for Taxes provided by
Sublessor to Sublessee at least thirty (30) days prior to the first day of the
fiscal year (the "Estimated Tax Statement"). Sublessor, in good faith, shall
have the right to provide adjusted Estimated Tax Statements during any fiscal
year, and in the event Sublessor fails to provide an Estimated Tax Statement
thirty (30) days prior to commencement of any fiscal year, Sublessee shall
continue to pay Additional Rent for Taxes based upon the immediately preceding
Estimated Tax Statement until such time as Sublessor provides Sublessee with a
new Estimated Tax Statement. In the event that said tax fund payments were not
adequate to pay Sublessee's share of such real estate taxes for a given fiscal
year, Sublessee shall pay to Sublessor the amount by which such aggregate is
less than the amount of said share, such payment to be made within thirty (30)
days after Sublessee's receipt of a notice from Sublessor of such amount
together with the applicable Tax Bill and Sublessor's calculation of Sublessee's
proportionate share of real estate taxes. Any surplus tax fund payments shall be
accounted for to Sublessee after payment by Sublessor of the real estate taxes
on account of which they were made, and shall be credited by Sublessor against
future tax fund payments or refunded to Sublessee at Sublessee's 


                                       24
<PAGE>   31

option. The two immediately preceding sentences shall survive the expiration or
sooner termination of this Sublease.

         5.3      Utilities.

                  (a)      Sublessee shall be responsible for and shall pay
                           prior to delinquency all charges for water,
                           electricity, steam, telephone and other utilities and
                           services rendered or supplied to the Sublease
                           Premises. If reasonably possible, all utilities,
                           including electricity (but specifically excluding
                           telephone, which telephone service and lines and
                           installation of lines shall be at Sublessee's sole
                           cost and expense), will be separately metered and
                           provided directly by the utility company. If not,
                           Sublessor may submeter the Subleased Premises. In
                           such event, the cost of the submeter and connecting
                           the utility lines brought to the Subleased Premises
                           to those lines installed in the Subleased Premises as
                           part of the Base Building Work shall be paid by
                           Sublessee to Sublessor. The foregoing costs may be
                           deducted from the Tenant Allowance. Sublessee shall
                           pay to Sublessor as additional rent (a) all costs and
                           expenses of any such utilities registered by any such
                           submeter and (b) with respect to any such utility
                           that shall not be provided directly by the applicable
                           utility and shall not be submetered, Sublessee's
                           Proportionate Share of the utility expenses (which
                           shall include costs for electrical energy not
                           measured by any such submeter and costs for hot and
                           cold water for ordinary cleaning, toilet, lavatory
                           and drinking purposes, and for all Permitted Uses of
                           Sublease and costs for gas for all Permitted Uses of
                           Sublease) based on the rentable square footage of the
                           Sublease Premises in relation to the rentable square
                           footage of the Building. To the extent that Sublessee
                           does not receive electricity, steam and other
                           utilities (specifically excluding telephones)
                           directly from a third-party utility provider,
                           Sublessor shall cause such utilities to be furnished
                           to the Sublease Premises through those building
                           systems set forth on Exhibit F-2 hereof, twenty-four
                           (24) hours per day, seven (7) days per week.
                           Furthermore, notwithstanding anything to the contrary
                           contained herein, the amount payable by Sublessee (on
                           a unit cost basis) for any such utility service shall
                           not exceed Sublessor's actual out-of-pocket cost (on
                           a unit cost basis) of causing such utility to be
                           furnished to the Building subject to the terms set
                           forth herein.

                  (b)      By reason of Sublessee's use of condenser water for
                           its HVAC system, Sublessee shall also pay as
                           additional rent to Sublessor, Sublessee's allocable
                           share of the costs for water produced in total by the
                           central plant of the Building. Sublessee's allocable
                           share of such costs shall be determined by BTU or
                           similar metering or by such other standard industrial
                           practice as Sublessor may reasonably employ.



                                       25
<PAGE>   32

                  (c)      Sublessee acknowledges that it is installing certain
                           equipment that shall serve the Sublease Premises
                           exclusively and that the electricity consumed by such
                           equipment shall be measured by a meter or submeter.
                           The cost of the meter or submeter and installation of
                           the meter or submeter shall be at Sublessee's sole
                           cost and expense. The foregoing costs may be deducted
                           from the Tenant Allowance.

Sublessor shall not be liable in any way to Sublessee for any failure or defect
in the supply or character of electrical energy furnished to the Sublease
Premises by reason of any requirement, act or omission of the public utility or
utility provider serving the Building with electricity unless due to the act or
omission of Sublessor. Sublessee's use of electrical energy in the Sublease
Premises shall not at any time exceed the capacity of any of the electrical
conductors and equipment in or otherwise serving the Sublease Premises as of the
Term Commencement Date. Sublessee agrees that it will not make any alteration to
the electrical equipment in the Sublease Premises without the prior written
consent of Sublessor in each instance first obtained in accordance with the
provisions of Sections 8 and 9 hereof. Sublessee, at its own expense, shall
replace all light fixtures, bulbs, tubes, lamps, lenses, globes, ballasts and
switches initially installed by Sublessor. If Sublessee is using a
disproportionately high amount of water and/or utilities in relation to other
tenants or occupants in the Building, Sublessor may assess Sublessee as
additional rent charges for such excessive consumption of water and/or utilities
(collectively, "Excess Utilities") if the Sublessee's use is disproportionately
high. Sublessee shall pay all bills and/or invoices for Excess Utilities within
thirty (30) days after receipt of a bill and/or invoice together with
Sublessor's calculation of the same. Sublessor shall not charge Sublessee any
mark-up for the Excess Utilities and Sublessee shall pay no more than Sublessee
would pay if it received the utilities in question from the third-party provider
serving the Building.

         Provided Sublessee is not in default hereunder beyond any applicable
notice and grace period, Sublessee shall have the right to inspect, copy and
audit those bills and/or invoices for Excess Utilities which serve as the basis
for Sublessee's Excess Utility bill provided Sublessee requests such an
inspection or audit within thirty (30) days after receipt from Sublessor of a
bill for Excess Utilities. Sublessor shall, within thirty (30) days after
receipt of Sublessee's written request hereunder, make available to Sublessee
such bills and/or invoices. If an audit together with an engineering report
(paid for by Sublessee and reasonably acceptable to Sublessor) indicate a
disproportionately low usage, Sublessor will pay to Sublessee, within thirty
(30) days after Sublessor or Sublessee discovers that Sublessee's usage of water
and/or utilities is disproportionately low ("Low Usage"), a refund that
compensates Sublessee for its disproportionately low usage.

         5.4 Interruption or Curtailment of Services. Sublessor reserves the
right to interrupt, curtail, stop or suspend the furnishing of services and the
operation of Building systems, when necessary by reason of accident or
emergency, or of repairs, alterations, replacements or improvements in the
reasonable judgment of Sublessor desirable or necessary to be made, or by reason
of difficulty or inability in securing supplies or labor, or of strikes, or of
any other cause beyond the reasonable control of Sublessor (other than lack of
funds), whether such other cause be similar or dissimilar to those herein above



                                       26
<PAGE>   33

specifically mentioned, until said cause has been removed. Notwithstanding
anything contained herein to the contrary, rent hereunder shall abate if the
entire Sublease Premises are rendered untenantable for thirty (30) consecutive
business days, Sublessee does not use any portion of the Sublease Premises and
such interruption of services is due to Sublessor's negligence or omission or
willful misconduct and not caused by Sublessee's negligence, omission or willful
misconduct. Except where impossible due to emergency conditions or conditions
beyond Sublessor's control (other than lack of funds), Sublessor agrees to
provide to Sublessee four (4) days' advance notice of any such interruptions,
curtailments, stoppages and suspensions of service or Building systems. Except
as provided herein, Sublessor shall not have any responsibility or liability for
any such interruption, curtailment, stoppage, or suspension of services or
systems unless due to Sublessor's negligence or omission or willful misconduct,
except that Sublessor shall exercise reasonable diligence to eliminate the cause
of same and to minimize the effects of the same.

         5.5 Payment to Mortgagee. Sublessor reserves the right to provide in
any mortgage given by it of the Main Premises that some or all rents, issues,
and profits and all other amounts of every kind payable to Sublessor under this
Sublease shall be paid directly to mortgagee for Sublessor's account and
Sublessee covenants and agrees that it will, after receipt by it of written
notice from Sublessor designating such mortgagee to whom payments are to be made
by Sublessee, pay such amounts thereafter becoming due directly to such
mortgagee until excused therefrom by written notice from such mortgagee.

         5.6 Utility Deregulation. To the extent permitted by law, Sublessor or
Landlord shall have the right at any time and from time to time during the Term
to contract for or purchase electrical service from any company or third party
providing electricity services (the "Electricity Service Provider"), which
contract or purchase shall in Sublessor's reasonable opinion be beneficial to
the occupants of the Building or of the Boston University Medical Campus taken
as a whole. Sublessee, at no cost to Sublessee, agrees to reasonably cooperate
with Landlord, Sublessor and the Electricity Service Provider and at all times
and, as reasonably necessary, and on reasonable advance notice, shall allow
Landlord, Sublessor, and the Electricity Service Provider reasonable access to
any electrical lines, feeders, risers, wiring and any other such machinery
within the Sublease Premises. Landlord and Sublessor (unless due to Sublessor's
negligence or omission or willful misconduct) shall not be liable or responsible
for any loss, damage, or expense that Sublessee may sustain or incur by reason
of any change, failure, interference, disruption or defect in the supply or
character of the electric energy furnished to the Sublease Premises, or if the
quantity or character of the electric energy supplied by the Electricity Service
Provider is no longer available or suitable for Sublessee's requirements, and no
such change, failure, defect, unavailability or unsuitability shall constitute
an actual or constructive eviction, in whole or in part, or entitle Sublessee to
any abatement or diminution of rent (except as may be expressly provided
herein), or relieve Sublessee from any of its obligations under the Sublease.

         5.7 HVAC Services. It is Sublessor's intention that there shall be a
separate HVAC system serving each floor within the Building and accordingly,
there may be one HVAC system serving the ground floor of the Sublease Premises
and a separate HVAC 



                                       27
<PAGE>   34

system serving the second floor of the Sublease Premises. Sublessee hereby
agrees that any such HVAC system exclusively serving the Sublease Premises (or a
portion thereof) shall be maintained and repaired at the sole cost and expense
of Sublessee and in such a manner so it is in good working condition during the
Term and upon the expiration or sooner termination of this Sublease (provided
that, notwithstanding anything to the contrary contained in this Sublease, with
respect to any replacement to or of any HVAC system, exclusively serving the
Sublease Premises (or a portion thereof), to the extent the cost of such
replacement should be considered to be a capital expenditure under GAAP, (i)
Sublessor shall make such replacement, (ii) the capital expenditure shall be
amortized, with interest at the prime rate, over its estimated useful life
according to GAAP and (iii) Sublessee shall reimburse Sublessor as additional
rent an amount equal to the product of (x) the cost of the capital expenditure
(together with interest as aforesaid) times (y) a fraction, the numerator of
which shall be the number of years remaining in the Term (as it may be extended
pursuant to Section 2.3 hereof) and the denominator of which shall be the number
of years over which the capital expenditure shall be amortized. Any payments to
be made as additional rent in the preceding clause (iii) shall be made in equal
installments at the commencement of each lease year remaining in the Term (as it
may be extended pursuant to Section 2.3 hereof). By way of example, if the
replacement of an HVAC system exclusively serving the Sublease Premises (or a
portion thereof) is $60,000 and is amortized over ten (10) years and there are
three (3) lease years remaining in the Term (as it may be extended pursuant to
Section 2.3 hereof), Sublessee shall pay at the commencement of each lease year
remaining in the Term as additional rent $6,000 (together with interest as
aforesaid). Sublessor agrees that Sublessee shall have twenty-four (24) hour per
day/365(66) days per year temperature control over an HVAC system serving the
Sublease Premises or a portion thereof. Temperature control for purposes of this
Section 5.7 shall be tied to the temperature control for the Building and
conform to the specifications more fully set forth on Exhibit F-2 hereto.
Accordingly, should Sublessee's particular use require any additional special
temperature controls, Sublessee shall be responsible for installing such HVAC
systems. To the extent that an HVAC System serving the Sublease Premises (or a
portion thereof) serves other premises as well, Sublessee shall be billed for
HVAC services for the whole of the Sublease Premises or that portion of the
Sublease Premises which is served by an HVAC system also serving other premises
(a "Building HVAC System") as set forth in the next succeeding sentences. To the
extent a Building HVAC System serves the Sublease Premises (or a portion
thereof), Landlord shall provide HVAC services to the Sublease Premises or that
portion of the Sublease Premises during the hours of 8:00 A.M. to 6:00 P.M., and
such HVAC services shall either be billed or assessed as additional rent based
on (i) readings as recorded by the submeter or (ii) Sublessee's Proportionate
Share of the HVAC services. In any event, each HVAC system serving the Sublease
Premises (or any portion thereof) shall conform to the specifications therefor
set forth on Exhibit F-2 hereto. Any HVAC services required by Sublessee before
or after the foregoing hours through a Building HVAC System or any Excess
Utilities used by Sublessee shall be at Sublessee's sole cost and expense,
Sublessee hereby agreeing to pay within thirty (30) days of receipt of a bill
for such Excess Utilities or such overtime HVAC services at overtime rates
charged by the Building from time to time (which shall not exceed Sublessor's
actual out-of-pocket cost (on a unit cost basis) of providing such HVAC
service). In addition, Sublessee shall notify Sublessor and 



                                       28
<PAGE>   35

Landlord at least 24 hours in advance of any overtime Building HVAC System HVAC
services that Sublessee shall require.

5.8      Sublessor Services.

                  (a)      Domestic Water. Sublessor shall furnish or cause
                           Landlord to furnish twenty-four (24) hours per day,
                           seven (7) days per week, hot and cold water to the
                           Sublease Premises (and to lavatories in common areas)
                           for ordinary cleaning, toilet, lavatory and drinking
                           purposes (in each case, as contemplated by, and in
                           accordance with the specifications therefor set forth
                           on Exhibit F-2 hereof).

                  (b)      Repairs and Other Services. Except as otherwise
                           provided in Article 14, and subject to Sublessee's
                           obligations in Article 10 and Section 5.7 or as
                           otherwise agreed in writing by the parties hereto,
                           Sublessor shall (a) keep and maintain in good
                           operating condition the Building's sanitary,
                           electrical, elevator, heating, air conditioning,
                           ventilation, vacuum, water, sewer, plumbing,
                           mechanical, fire safety and other systems
                           (specifically excluding (except to the extent
                           otherwise provided in Section 5.7 hereof) those
                           systems used exclusively by Sublessee or individual
                           lessees or occupants in the Building), (b) provide
                           cleaning services to the common areas of the Building
                           according to the cleaning standards generally
                           prevailing in comparable research/development
                           buildings in the City of Boston, (c) keep all
                           driveways, roadways, walkways, if any, on the
                           Property clean, and remove all snow therefrom and
                           cause the Landlord to do the same with respect to the
                           Parking Facility, and (d) provide grounds maintenance
                           to all landscaped areas according to the standards
                           generally prevailing in comparable
                           research/development buildings in the City of Boston.
                           Sublessor shall also provide to the Sublease Premises
                           and to Sublessee, (A) twenty-four (24) hours per day,
                           seven (7) days per week elevator service (through 2
                           passenger elevators) and (B) during hours of 9:00
                           A.M. to 5:00 P.M., Monday through Friday (excluding
                           all federal and state and municipal holidays), use of
                           the Building's loading docks and freight elevators
                           subject to periods of disuse, Sublessor's maintenance
                           obligations and Force Majeure Delays.

         5.9 Additional Rent. All payments due under this Sublease from
Sublessee to Sublessor, Landlord, and/or any third party and/or provider
including without limitation Additional Rent, Additional Rent for Taxes, utility
expenses, Parking Rent, charges for the emergency generator as set forth in
Exhibit F hereto, and all other costs and expenses incurred by or assessed
against Sublessee hereunder shall constitute "additional rent" for purposes of
this Sublease. Sublessee hereby agrees to pay as additional rent, Sublessee's
Proportionate Share of actual out-of-pocket costs incurred for the installation,
maintenance 



                                       29
<PAGE>   36

and operation by Sublessor of the emergency generator and the use by Sublessee
of the emergency generator as described herein and in the Work Letter Agreement.

         5.10 Government Award or Grant. If any benefits are specifically
granted or awarded to Sublessor or Sublessee by any governmental agency or other
authority due to or on account of Sublessee's particular use of the Sublease
Premises, Sublessee shall receive 100% of any such economic benefit attributable
to its particular use (over the same time period as such economic benefit is
granted to Sublessor) and any such economic benefit actually received by
Sublessor shall be applied as a rent credit against Yearly Fixed Rent and
Additional Rent after deducting all expenses of Sublessor incurred in the
securing, administration and maintenance of such benefits (by amortizing the
same over the remaining Term of the Sublease on a straight-line basis).
Sublessor shall use reasonable efforts and cooperate in good faith at no
additional cost or expense to Sublessor to assist Sublessee in Sublessee's
efforts to obtain any such awards or grants by governmental authorities or
agencies. Notwithstanding the foregoing sentences, in no event shall any loan
financing, bond financing or anything in the nature thereof extended to
Sublessor or Landlord in connection with the financing of the Property and
Building including the Sublease Premises and/or any real estate tax abatement,
pilot program or anything in the nature thereof be considered a governmental
award or grant.

6.       CHANGES OR ALTERATIONS BY SUBLESSOR

         Sublessor reserves the right, exercisable by itself or its nominee, at
any time and from time to time without the same constituting an actual or
constructive eviction and without incurring any liability to Sublessee therefor
or otherwise affecting Sublessee's obligations under this Sublease, to make such
changes, alterations, additions, improvements, repairs or replacements in or to
the Building (including the Sublease Premises with respect to those repairs that
Sublessor is required or permitted to make pursuant to the express terms of the
other provisions of this Sublease) and the fixtures and equipment thereof, as
well as in or to the street entrances, halls, passages, elevators, escalators,
and stairways thereof, as it may reasonably deem necessary or desirable, and to
change the arrangement and/or location of entrances or passageways, doors and
doorways, and corridors, elevators, stairs, toilets, or other public parts of
the Building, provided, however, that except in cases of emergency, Sublessor's
exercise of its rights hereunder shall (A) not compromise the security system
installed by Sublessee and approved by Sublessor (if its approval is required
hereunder), (B) be done after giving reasonable prior notice to Sublessee and
(C) (i) shall be done in a manner consistent with the maintenance of the
Building as a good quality research/development building (by reference to other
comparable research/development buildings in the Boston University Medical
Campus), (ii) shall not reduce the usable floor area of the Sublease Premises
and (iii) shall not (other than to a de minimis extent) adversely affect
Sublessee's use of the Sublease Premises for the Permitted Uses (including,
without limitation, Sublessee's access thereto). Nothing contained in this
Article shall be deemed to relieve Sublessee of any duty, obligation or
liability of Sublessee with respect to making or causing to be made any repair,
replacement or improvement or complying with any law, order or requirement of
any governmental or other authority. Neither this Sublease nor any use by
Sublessee shall give Sublessee any right or easement to use, or the use of any
door or 



                                       30
<PAGE>   37

any passage or any concourse connecting with any other building or to any public
convenience, and the use of such doors, passages and concourses and of such
conveniences may be regulated or discontinued at any time and from time to time
by Landlord or Sublessor without notice to Sublessee and without affecting the
obligation of Sublessee hereunder or incurring any liability to Sublessee
therefor.

7.       FIXTURES, EQUIPMENT AND IMPROVEMENTS - REMOVAL BY SUBLESSEE

         Except as otherwise expressly provided in Section 3.1A hereof or this
Section 7, all fixtures, equipment, improvements and appurtenances attached to
or built into the Sublease Premises prior to or during the Term, whether by
Sublessor at its expense or at the expense of Sublessee (either or both) or by
Sublessee shall be and remain part of the Sublease Premises and shall not be
removed by Sublessee at the end of the Term unless otherwise expressly provided
in this Sublease. Except as otherwise expressly provided in Section 3.1A hereof
or this Section 7, where not permanently affixed to the Sublease Premises, and
if furnished and installed by and at the sole expense of Sublessee (but
specifically excluding all items paid for by the Tenant Allowance), all
removable electrical fixtures, cables, carpets, hoods and equipment, drinking or
tap water facilities, furniture, or trade fixtures or business equipment shall
not be deemed to be included in such fixtures, equipment, improvements and
appurtenances and may be, and upon the request of Sublessor will be, removed by
Sublessee upon the condition that such removal shall not damage the Sublease
Premises, the Building or any building systems serving the Sublease Premises or
Building, or create an unsafe condition, and that any damage to the Sublease
Premises or the Building arising from such removal shall be promptly repaired by
Sublessee in a manner satisfactory to Sublessor subject to Sublessor's rights
pursuant to Article 15 of this Sublease. The obligations of Sublessee under the
foregoing sentence shall survive the expiration or sooner termination of this
Sublease.

8.       ALTERATIONS AND IMPROVEMENTS BY SUBLESSEE

         Except as otherwise expressly provided herein, Sublessee shall make no
alterations, installations, removals, additions or improvements in or to the
Sublease Premises without Sublessor's prior written consent and then only by
contractors or mechanics approved by Sublessor. No installations or work shall
be undertaken or begun by Sublessee until Sublessor has approved written plans
and specifications therefor, and no amendments or additions to such plans and
specifications shall be made without prior written consent of Sublessor. Any
such work, alterations, installations, removals, additions and improvements
shall be done at the sole expense of Sublessee and at such times and in such
manner as Sublessor may from time to time reasonably designate. If Sublessee
shall make any alterations, decorations, installations, removals, additions or
improvements which Sublessee may, under Article 3 or 7, remove, then Sublessor
may elect, at the time of approval thereof, to require Sublessee at the
expiration of this Sublease to remove the same and to deliver to Sublessor the
Sublease Premises as required under Article 16.



                                       31
<PAGE>   38

         Notwithstanding anything contained herein to the contrary, Sublessee
may make non-structural alterations without the consent of Sublessor (being
alterations which do not affect the structure of the Building and/or any
Building systems including the mechanical, plumbing or electrical systems
serving the Building) which are less than $20,000 in any one instance, provided,
however, that (a) Sublessee shall provide Sublessor with not less than thirty
(30) days prior written notice before commencing such alterations and copies of
all permits necessary for such alterations, (b) said notice shall contain a
certification by Sublessee that such alteration (i) is a non-structural
alteration (for purposes of this Sublease) and (ii) shall not cost more than
$20,000, and (c) such alterations are performed in accordance with the terms of
this Sublease. All structural alterations (regardless of the cost) and all
non-structural alterations costing $20,000 or more are subject to Landlord's
prior written consent. With respect to those consent and approval rights of
Sublessor set forth in Section 8 hereof, provided there is no default (after the
expiration of all applicable notice and cure periods) under this Sublease,
Sublessor shall not unreasonably withhold, delay or condition its consent or
approval so long as the proposed alterations and/or the architect, engineer or
other applicable persons or entities selected by Sublessee to undertake the
proposed alterations, are consistent with the quality of the Building (including
the Base Building Work), shall not violate any applicable laws, shall maintain
harmonious labor relations and shall not interfere with the structural integrity
and/or structural elements of the Building, operations and rights of other
occupants and tenants within the Building or any other construction in or about
the Building. In addition, Sublessee shall reimburse Sublessor for all
reasonable costs incurred by Sublessor in reviewing any plans and specifications
and contracts necessary to undertake such proposed alterations.

9. SUBLESSOR'S CONTRACTORS - MECHANICS' AND OTHER LIENS - STANDARD OF
   SUBLESSEE'S PERFORMANCE - COMPLIANCE WITH LAWS

         Whenever Sublessee shall make any alterations, decorations,
installations, removals, additions or improvements or do any other work in or to
the Sublease Premises, Sublessee shall strictly observe the following covenants
and agreements:

         a.       In no event shall any materials or equipment (other than
                  freestanding equipment installed on or before the Term
                  Commencement Date or after-acquired freestanding equipment
                  with respect to which Sublessor hereby agrees to execute, and
                  to cause Landlord to execute, a commercially reasonable form
                  of Landlord Consent of Installation and Waiver) be
                  incorporated in or added to the Sublease Premises in
                  connection with any such alteration, decoration, installation,
                  addition or improvement which is subject to any lien, charge,
                  mortgage or other encumbrance of any kind whatsoever or is
                  subject to any security interest or any form of title
                  retention agreement. Any mechanic's lien filed (other than as
                  a result of the acts or omissions of Sublessor or Landlord)
                  against the Sublease Premises or the Building for work claimed
                  to have been done for, or materials claimed to have been
                  furnished to Sublessee shall be discharged by Sublessee at the
                  expense of Sublessee, by filing the bond required by law or
                  otherwise, upon the earlier of thirty (30) days from (i)
                  Sublessee's 



                                       32
<PAGE>   39

                  knowledge of such mechanic's lien or (ii) Sublessee's receipt
                  of notice from Sublessor of the existence of such mechanic's
                  lien. If Sublessee fails so to discharge any such lien,
                  Sublessor may do so at Sublessee's expense and Sublessee shall
                  reimburse Sublessor for any expense or cost incurred by
                  Sublessor in so doing within fifteen (15) days after rendition
                  of a bill therefor.

         b.       All installations or work done by Sublessee under this or any
                  other Article of this Sublease shall be at its own expense
                  (unless otherwise expressly provided) and shall at all times
                  comply with (i) laws, rules, orders and regulations of
                  governmental authorities having jurisdiction thereof; (ii)
                  orders, rules and regulations of any Board of Fire
                  Underwriters, or any other body hereafter constituted
                  exercising similar functions, and governing insurance rating
                  bureaus; (iii) plans and specifications, if any, prepared by
                  and at the expense of Sublessee theretofore submitted to
                  Sublessor for its prior written approval (subject to the
                  provisions of Article 8).

                  Sublessee shall procure all necessary permits before
                  undertaking any work in the Sublease Premises; do all such
                  work in a good and workmanlike manner, employing materials of
                  good quality and complying with all governmental requirements,
                  and defend, save harmless, exonerate and indemnify Landlord
                  and Sublessor from all injury, loss or damage to any person or
                  property occasioned by or growing out of such work, (except to
                  the extent arising out of the negligence or omission or
                  willful misconduct of Sublessor).

10.      REPAIRS AND SECURITY BY SUBLESSEE

         Sublessee shall keep or cause to be kept all and singular the Sublease
Premises neat and clean and maintain in such good repair, order and condition as
the same are in on the Term Commencement Date or may be changed during the Term
hereof (in accordance with the terms and conditions of this Sublease),
reasonable use and wear thereof and damage by fire or casualty excepted;
provided, however, that in no event shall Sublessee be required to make
structural repairs or replacements or repairs or replacements to the Building
systems which are expressly made by the terms of the Sublease the responsibility
of the Sublessor and/or Landlord unless and to the extent such damage is caused
by Sublessee. Without limiting the generality of the foregoing, Sublessee shall
replace all windows with glass of the same quality whenever broken as a result
of negligence or misconduct attributable to Sublessee. Sublessor shall maintain
or shall cause Landlord to maintain in good repair, order and condition and
according to standards generally prevailing in comparable research/development
buildings in the City of Boston the structural and common elements of the
Building and Lot, including those Building systems serving the Subleased
Premises and/or the common areas of the Building and shall make all necessary
repairs and replacements required in connection therewith.

         Subject to Sublessor's rights pursuant to Section 15.4 of the Sublease,
(a) Sublessee shall make, as and when needed as a result of misuse by, or
neglect or improper conduct (including, without limitation, the placement of any
weight exceeding floor load) of 



                                       33
<PAGE>   40

Sublessee or Sublessee's servants, employees, agents, invitees or licensees, all
repairs in and about the Sublease Premises necessary to preserve them in such
repair, order and condition, which repairs shall be in quality and class equal
to the original work, and (b) except to the extent otherwise provided in Section
5.7 hereof, Sublessee shall replace, keep and maintain in good operating
condition all systems exclusively serving the Sublease Premises including any
separate heating and air conditioning system serving the Sublease Premises, if
any such separate system is installed, all plumbing and sewage facilities within
the Sublease Premises (including all such facilities outside of the Sublease
Premises, but exclusively serving the Sublease Premises), any other mechanical
and electrical or other special systems and equipment wherever located if such
systems and equipment were installed at Sublessee's request or serve exclusively
the Sublease Premises, fixtures, interior walls, floors, ceilings and signs
within Sublease Premises.

11.      INSURANCE, INDEMNIFICATION, EXONERATION AND EXCULPATION

         11.1 Insurance. Sublessee shall maintain at its sole expense (a)
Comprehensive Public Liability Insurance naming Landlord, Sublessor, Sublessee
and (whenever Landlord or Sublessor shall so request) any mortgagee holding a
mortgage on the Sublease Premises and/or Building as additional insureds against
all claims and demands for injury to or death of persons or damage to property
which may be claimed to have occurred upon the Sublease Premises in amounts not
less than Five Hundred Thousand Dollars ($500,000) for property damage, One
Million Dollars ($1,000,000) for injury or death of one person, and Three
Million Dollars ($3,000,000) for injury or death of more than one person in a
single accident, and from time to time thereafter in such higher amounts, if
procurable, as may be reasonably required by Landlord or Sublessor or a
mortgagee or lender or any successor or replacement lenders and are customarily
carried by responsible office, research and development and laboratory tenants
in the City of Boston, and (b) so-called contents and improvements insurance
adequately insuring all property belonging to or removable by Sublessee and
situated in the Sublease Premises.

         11.2 Certificates of Insurance. Such insurance shall be effected with
insurers authorized to do business in Massachusetts under valid and enforceable
policies, and any such liability policies shall name Landlord, Sublessor,
Sublessee and any additional parties designated by Landlord or Sublessor
pursuant to Section 11.1 as the insureds or additional insureds, as their
respective interests appear. Such insurance shall provide that it shall not be
canceled without at least thirty (30) days' prior written notice to each insured
named therein. On or before the Term Commencement Date and thereafter prior to
the expiration of each expiring policy, original copies of the policies provided
for in Section 11.1 issued by the respective insurers, or certificates or
binders of such policies setting forth in full the provisions thereof and issued
by such insurers, shall be delivered by Sublessee to Landlord and Sublessor and
certificates as aforesaid of such policies shall upon request of Landlord and
Sublessor be delivered by Sublessee to the holder of any mortgage affecting the
Sublease Premises.

         11.3 General. Sublessee shall save Landlord and Sublessor harmless, and
shall exonerate and indemnify Landlord and Sublessor, from and against any and
all claims, 



                                       34
<PAGE>   41

liabilities or penalties asserted by or on behalf of any person, firm,
corporation or public authority:

         a.       On account of or based upon any injury to person or loss of or
                  damage to property sustained or occurring on the Sublease
                  Premises on account of or based upon the act, omission, fault,
                  negligence or misconduct of any person whomsoever (other than
                  Landlord, Sublessor or their respective agents, contractors,
                  employees, invitees or licensees);

         b.       On account of or based upon any injury to person or loss of or
                  damage to property, sustained or occurring elsewhere (other
                  than on the Sublease Premises) in or about the Building (and,
                  in particular, without limiting the generality of the
                  foregoing, on or about the elevators, stairways, public
                  corridors, sidewalks, concourses, arcades, malls, galleries,
                  vehicular tunnels, approaches, areaways, roof, or other
                  appurtenances and facilities used in connection with the
                  Building or Sublease Premises) arising out of the use or
                  occupancy of the Building or Sublease Premises by Sublessee,
                  or any person claiming by, through, or under Sublessee, except
                  to the extent such injury, loss or damage arose out of or
                  resulted from the act, omission, fault, negligence or
                  misconduct of Landlord, Sublessor or their respective agents,
                  contractors, employees, invitees or licensees. Sublessor
                  hereby agrees to use reasonable efforts to give Sublessee
                  prompt notice of any such claim after Sublessor or Landlord
                  obtains knowledge thereof;

         c.       On account of or based upon (including monies due on account
                  of) any work or thing whatsoever done in the Sublease Premises
                  during the Term of this Sublease performed by any person other
                  than Landlord, Sublessor or anyone claiming by, through or
                  under Landlord or Sublessor; and

         d.       On account of or resulting from the failure of Sublessee to
                  perform and discharge any of its covenants and obligations
                  under this Sublease;

and, in respect of any of the foregoing items (a)-(d), from and against all
costs, expenses (including reasonable attorneys' fees), and liabilities incurred
in or in connection with any such claim, or any action or proceeding brought
thereon; and in case of any action or proceeding brought against Landlord or
Sublessor by reason of any such claim, Sublessee upon notice from Landlord or
Sublessor shall at Sublessee's expense resist or defend such action or
proceeding and employ counsel therefor reasonably satisfactory to Landlord or
Sublessor, as the case may be, it being agreed that such counsel as may act for
insurance underwriters of Sublessee engaged in such defense shall be deemed
satisfactory.

         11.4 Property of Sublessee. In addition to and not in limitation to the
foregoing, Sublessee covenants and agrees that all merchandise, furniture,
fixtures and property of every kind, nature and description which may be in or
upon the Sublease Premises or Building, in the public corridors, or on the
sidewalks, areaways and approaches adjacent thereto, during the Term of this
Sublease, shall be at the sole risk and hazard of Sublessee, and that if the
whole or any part thereof shall be damaged, destroyed, stolen or removed 



                                       35
<PAGE>   42

from any cause or reason whatsoever, no part of said damage or loss shall be
charged to, or borne by Sublessor or Landlord.

         11.4A Release and Waiver of Subrogation. Each of Sublessor and
Sublessee (the "damaged party") hereby releases the other party (the "released
party") from any liability to the damaged party on account of any damage to the
damaged party's property arising out of any casualty or other loss included
within a standard form of "all-risk" property insurance policy used in the
Commonwealth of Massachusetts (or, if the coverage provided thereby is broader,
the fire and casualty insurance actually carried by the damaged party),
excepting, however, any damage which is the result of the fault of negligence of
the released party or its employees, contractors, agents or invitees. Neither
Sublessor nor Sublessee shall obtain or accept any insurance policy which would
be invalidated by or would conflict with such release; except that either of the
Sublessor or Sublessee shall have the right to obtain a policy of insurance that
would be invalidated by or would conflict with such release (and, the release
shall not apply with respect to damage covered by such a policy), if it is no
longer possible for such party procuring the insurance in question to obtain a
policy which would not be invalidated and would not conflict with such release,
and such party so notifies the other party.

         11.5 Bursting of Pipes, etc. Neither Landlord nor Sublessor shall be
liable for any injury or damage to persons or property resulting from fire,
explosion, falling plaster, steam, gas, electricity, electrical disturbance,
water, rain or snow or leaks from any part of the Building or from the pipes,
appliances or plumbing works or from the roof, street or sub-surface or from any
other place or caused by dampness or by any other cause of whatever nature,
unless caused by or due to the willful misconduct or negligence of Landlord,
Sublessor or their respective agents, servants or employees; nor shall Landlord,
Sublessor or their respective agents be liable for any such damage caused by
other tenants or persons in the Building or caused by operations in construction
of any private work or public or quasi-public work performed by any person other
than Landlord, Sublessor or anyone claiming by, through or under Landlord or
Sublessor; nor shall Landlord or Sublessor be liable for any latent defect in
the Sublease Premises or in the Building, unless Sublessee provides Sublessor
with written notice of such latent defect not more than ten (10) months after
the Term Commencement Date and Sublessor fails to diligently repair it.

         11.6 Repairs and Alterations - No Diminution of Rental Value. Except as
otherwise provided in this Sublease and except to the extent resulting from
Sublessor's or Landlord's willful misconduct or negligence (or that of their
respective agents, servants or employees), there shall be no allowance to
Sublessee for diminution of rental value and no liability on the part of
Sublessor by reason of inconvenience, annoyance or injury to Sublessee arising
from any repairs, alterations, additions, replacements or improvements made by
Sublessor, Sublessee or others in or to any portion of the Building or Sublease
Premises, or in or to fixtures, appurtenances, or equipment thereof, or for
failure of Landlord, Sublessor or their respective others to make any repairs,
alterations, additions or improvements in or to any portion of the Building or
of the Sublease Premises, or in or to the fixtures, appurtenances or equipment
thereof, provided however that any such work 



                                       36
<PAGE>   43

performed by or on behalf of Sublessor shall be subject to the provisions of
Section 13.2 and Article 6.

         11.7 Sublessor's Insurance. Sublessor, throughout the Term, shall keep
or cause the Landlord to keep the Building insured for the "full replacement
value" thereof against loss or damage by perils customarily included under
standard "all-risk" policies. In addition, throughout the Term, Sublessor shall
maintain or cause the Landlord to maintain commercial general liability
insurance, in respect of the Building and the Lot and the conduct or operation
of business therein or thereon, with limits of not less than One Million
($1,000,000) Dollars combined single limit for bodily injury and property damage
liability in any one occurrence and Three Million ($3,000,000.00) Dollars in the
annual aggregate. Within thirty (30) days after request, Sublessor shall deliver
to Sublessee certificates of insurance, showing that the insurance required to
be maintained pursuant to the foregoing provisions of this Section 11.7 is in
force. All policies may be part of any blanket policies carried by Landlord or
Sublessor and shall be issued by insurers authorized to do business in
Massachusetts under valid and enforceable policies.

12.      ASSIGNMENT, MORTGAGING, SUBLETTING, ETC.

         Sublessee covenants and agrees that except as otherwise expressly
provided herein, neither this Sublease nor the term and estate hereby granted
nor any interest herein, will be assigned, mortgaged, pledged, encumbered or
otherwise transferred (whether voluntarily or by operation of law), and that
neither the Sublease Premises, nor any part thereof, will be encumbered in any
manner by reason of any act or omission on the part of Sublessee, or used or
occupied, or permitted to be used or occupied, or utilized for any reason
whatsoever, by anyone other than Sublessee, or for any use or purpose other than
as permitted hereunder, or be sublet, or offered or advertised for subletting,
without prior written consent of Sublessor and Landlord in every case, which
consent shall not be unreasonably conditioned, withheld or delayed.

         Sublessor's consent shall not be considered unreasonably withheld,
delayed or conditioned if: (1) in the event of a proposed transfer, the proposed
transferee's financial condition is such that, in the reasonable judgment of
Sublessor, such proposed transferee will be unable to fulfill all of its
obligations under the Sublease or the sub-sublease, as applicable for the
remainder of the Term or the term of the sub-sublease, as applicable; (2) the
proposed transferee's business is not suitable for the Building considering the
business of the other tenants and the Building's prestige or would result in a
violation of an exclusive right granted to another tenant in the Building; (3)
the proposed use is different than the Permitted Use; (4) the proposed
transferee is a government agency or occupant of the Building; (5) Sublessee is
in default after the giving of the applicable notice and the expiration of the
applicable grace period set forth herein; or (6) any portion of the Building or
Sublease Premises would become subject to additional or different governmental
laws or regulations as consequence of the proposed transfer and/or the proposed
transferee's use and occupancy of the Sublease Premises. Notwithstanding the
foregoing, Sublessor will not withhold its consent solely because the proposed
subtenant or assignee is an occupant of the Building if Sublessor does not have
space available for lease in the Building that is 



                                       37
<PAGE>   44

comparable to the space Sublessee desires to sublet or assign and available for
the length of term requested by such subtenant or assignee. Sublessee
acknowledges that the foregoing is not intended to be an exclusive list of the
reasons for which Sublessor may reasonably withhold its consent to a proposed
transfer. Any attempted transfer in violation of the terms of this Section
shall, at Sublessor's option, be void. Consent by Sublessor to one or more
transfers shall not operate as a waiver of Sublessor's rights as to any
subsequent transfers. In addition, Sublessee shall not, without Sublessor's
consent, publicly advertise the proposed rental rate for any transfer.

         For purposes of this Sublease, transfer shall mean the assignment
(collateral or otherwise), mortgage, sublease, transfer, pledge or encumbrance
by Sublessee of this Sublease or any interest therein or the grant by Sublessee
of any license, concession or other right of occupancy of the Sublease Premises
or any portion thereof.

         If Sublessee requests Sublessor's consent to a transfer, Sublessee,
together with such request for consent, shall provide Sublessor with the name of
the proposed transferee and the nature of the business of the proposed
transferee, the term, use, rental rate and all other material terms and
conditions of the proposed transfer, including, without limitation, a copy of
the proposed assignment, sublease or other contractual documents and evidence
reasonably satisfactory to Sublessor that the proposed transferee is financially
responsible. Notwithstanding Sublessor's agreement to act reasonably under this
Section, Sublessor may, within forty-five (45) days after its receipt of all
information and documentation required herein, either (1) consent to or
reasonably refuse to consent to such transfer in writing; or (2) if Sublessee
proposes to sublease or assign more than 1/3 of the Sublease Premises to a
third-party, cancel and terminate this Lease with respect to the portion of the
Sublease Premises that Sublessee proposes to assign or sublet, upon forty-five
(45) days' notice, in accordance with the recapture provisions set forth below.

         Notwithstanding the foregoing, provided Sublessee is not in default
after the giving of notice and the expiration of the applicable grace period set
forth herein, Sublessee shall have the right to make without Sublessor's prior
written consent, but with prior written notification to Sublessor, one or more
transfers to (a) a parent, subsidiary, an entity under common control with
Sublessee, or division of Sublessee, (b) any entity with which or into which
Sublessee may consolidate or merge, or (c) any person or entity acquiring all or
substantially all of the assets of Sublessee, provided that, simultaneously with
any such transfer if such transfer shall be an assignment, Sublessee shall
deliver to Sublessor an agreement in form and substance reasonably satisfactory
to Sublessor which contains an appropriate covenant of assumption by such
transferee of all obligations arising under this Sublease from and after the
effective date of such assignment; and provided further that Sublessee shall
have submitted to Sublessor prior thereto financial statements or other
materials reasonably satisfactory to Sublessor evidencing that such transferee
has financial resources necessary to fulfill its obligations under the Sublease
or the sub-sublease, as applicable. The foregoing transfers (a) - (c) shall be
referred to herein as "permitted transfers".



                                       38
<PAGE>   45

         With respect to an assignment or sublease (specifically excluding a
permitted transfer), Sublessor may have the right to recapture the portion of
the Sublease Premises that Sublessee proposes to assign or sublease if Sublessee
desires to sublease or assign more than one-third (1/3rd) of the Sublease
Premises to a third party. Sublessor must exercise (or forego) its recapture
rights within forty-five (45) days of its receipt of Sublessee's
sublease/assignment notice. In order to effectuate its recapture rights,
Sublessor must terminate the Sublease with respect to that portion of the
Sublease Premises which it is recapturing and Sublessee shall have no further
obligations with respect to that portion of the Sublease Premises which are
recaptured (and there shall be a pro rata reduction in Rent based upon the
rentable square footage of the recaptured portion of the Sublease Premises
relative to the rentable square footage of Sublease Premises prior to
recapture), except as specifically set forth herein, and Sublessee and Sublessor
shall work together in order to erect, if necessary, a demising wall to separate
the remainder of the Sublease Premises from that portion of the Sublease
Premises which is being recaptured and to take such other steps as shall be
necessary to make the portion of the Sublease Premises that is not being
recaptured into a self-contained, lawfully demisable rental unit. Any costs
borne by Sublessee and Sublessor in the immediately preceding sentence shall be
shared 50/50 between Sublessor and Sublessee and the 50% of the costs
attributable to Sublessee shall be treated as additional rent under this
Sublease. Notwithstanding anything contained herein to the contrary, Sublessor
shall not have any recapture right if less than one-third (1/3) of Sublease
Premises is proposed to be sublet/assigned. In addition, with respect to any
assignment or sublease (specifically excluding a permitted transfer), all
"Excess Rents" from such sublease or assignment shall be split equally between
Sublessor and Sublessee. "Excess Rents" means Sublessee's net profit from the
sublease/assignment after first deducting Sublessee's costs (which are
reasonable, actual, and documented with no markup) of the subleasing/assignment
(including commissions, legal fees, and tenant improvement costs amortized over
the entire term of the Sublease (which are reasonable, actual, and documented
with no markup) required to induce the Sublessee to sublease or the assignee to
accept an assignment); provided that in no event shall Excess Rents include any
fair market rent or other fair market consideration (which costs shall be
documented and approved by Sublessor) that the sub-sublessee/assignee pays to
Sublessee with respect to Sublessee's trade fixtures or personal property. In
the event Sublessor is requested to consent to an assignment of this Sublease or
a subletting of the Subleased Premises, Sublessee shall pay all costs and
expenses in connection with such assignment or subletting, including, without
limitation, any reasonable attorneys' fees of Sublessor in connection with its
review of the assignment or subletting documents, any cost of renovating,
altering or decorating the Subleased Premises for a new occupancy (if Sublessee
desires to do the same) and any leasing brokerage fees payable.

         Notwithstanding anything to the contrary set forth herein, if Sublessee
elects to transfer fifty percent (50%) or more of the Sublease Premises,
Sublessee shall have waived all rights under this Sublease to exercise the First
Right of Refusal (as hereinafter defined). The foregoing waiver shall not apply
to a permitted transfer except for those permitted transfers which result in a
change in control of Sublessee.



                                       39
<PAGE>   46

         The listing of any name other than that of Sublessee, whether on the
doors of the Sublease Premises or on the Building directory, or otherwise, shall
not operate to vest any right or interest in this Sublease or in the Sublease
Premises or be deemed to be the written consent of Sublessor mentioned in this
Article, it being expressly understood that any such listing is a privilege
extended by Sublessor revocable at will by written notice to Sublessee.

         If this Sublease is assigned, or if the Sublease Premises or any part
thereof is sublet or occupied by anybody other than Sublessee, and Sublessee is
in default hereunder beyond applicable notice and cure periods, Sublessor may at
any time and from time to time, collect rent and other charges from the
assignees, subtenant or occupant, and apply the net amount collected to the Rent
and other charges herein reserved, but no such assignment or collection shall be
deemed a waiver of this covenant, or the acceptance of the assignee, subtenant
or occupant as a tenant, or a release of Sublessee from the further performance
of covenants on the part of Sublessee herein contained, including without
limitation, Sublessee's obligation to pay the Yearly Fixed Rent and Additional
Rent or a release of the Guarantor under the Guaranty. The consent by Sublessor
to an assignment or subletting or occupancy shall not in any way be construed to
relieve Sublessee from obtaining the express consent in writing of Sublessor to
any further assignment or subletting or occupancy.

13.      MISCELLANEOUS COVENANTS

         13.1 Rules and Regulations. Sublessee and its servants, employees,
agents, visitors and licensees will faithfully observe such reasonable rules and
regulations as Landlord or Sublessor hereafter at any time or from time to time
may make and may communicate in writing to Sublessee and which in the reasonable
judgment of Landlord or Sublessor shall be necessary for the reputation, safety,
care or appearance of the Building and/or Lot, the proper use of the Building
(including the Sublease Premises) for vivarium purposes and research and
development purposes, or the preservation of good order therein, or the
operation or maintenance of the Building and/or Lot, or the equipment thereof,
or the comfort of tenants or others in the Building, provided, however, that in
the case of any conflict between the provisions of this Sublease and any such
Rules and Regulations, the provisions of this Sublease shall control. Sublessor
hereby agrees to apply the Rules and Regulations consistently as against all of
Sublessor's sublessees, provided further that (a) nothing contained in this
Sublease shall be construed to impose upon Landlord or Sublessor, as the case
may be, any duty or obligation to enforce such Rules and Regulations or the
terms, covenants or conditions in any other lease as against any other tenant
and (b) Landlord or Sublessor, as the case may be, shall not be liable to
Sublessee for a violation(s) of the same by any other tenant of the Building ,
or its respective servants, employees, agents, visitors, invitees or licensees.

         13.2 Access to Premises - Shoring. Sublessee shall, at reasonable times
and upon reasonable advance notice (except in the case of an emergency): (i)
permit Landlord or Sublessor to erect, use and maintain pipes, ducts and
conduits in and through the Sublease Premises, provided the same does not
materially reduce the floor area or materially or adversely affect the
appearance thereof; (ii) with, reasonable advance oral notice except in cases of
emergency, permit Landlord, Sublessor and any mortgagee and its representatives,



                                       40
<PAGE>   47

to have free and unrestricted access to and to enter upon the Sublease Premises
at all reasonable hours for the purposes of inspection or of making repairs,
replacements or improvements in or to the Sublease Premises or the Building or
equipment (including, without limitation, sanitary, electrical, heating, air
conditioning or other systems) or of complying with all laws, orders and
requirements of governmental or other authority or of exercising any right
reserved to Landlord or to Sublessor by this Sublease (including the right
during the progress of any such repairs, replacements or improvements or while
performing work and furnishing materials in connection with compliance with any
such laws, orders or requirements to take upon or through, or to keep and store
within, the Sublease Premises all necessary materials, tools and equipment); and
(iii) with reasonable advance oral notice, permit Landlord or Sublessor, at
reasonable times, to show the Sublease Premises during ordinary business hours
to any mortgagee, prospective purchaser of any interest of Landlord or Sublessor
in the Building, prospective mortgagee, or prospective assignee of any mortgage,
and during the period of twelve months prior to the termination date to any
person contemplating the leasing of the Sublease Premises or any part thereof.
If during the last month of the Term, Sublessee shall have removed all of
Sublessee's property therefrom, Sublessor may immediately enter and alter,
renovate and redecorate the Sublease Premises, without elimination or abatement
of Rent, or incurring liability to Sublessee for any compensation, and such acts
shall have no effect upon this Sublease. If Sublessee shall not be personally
present to open and permit entry into the Sublease Premises at any time when for
any reason an entry therein shall be necessary or permissible, Landlord,
Landlord's agents or Sublessor must nevertheless be able to gain such entry by
contacting a responsible representative of Sublessee, whose name, address and
telephone number shall be furnished by Sublessee. Provided that Landlord and
Sublessor shall incur no additional expense thereby, Landlord and Sublessor
shall exercise its rights of access to the Sublease Premises permitted under any
of the terms and provisions of this Sublease in such manner as to minimize to
the extent practicable interference with Sublessee's use and occupation of the
Sublease Premises.

         13.3 Accidents to Sanitary and other Systems. Sublessee shall give to
Sublessor promptly after it obtains knowledge thereof notice of any fire or
accident in the Sublease Premises or in the Building and of any damage to, or
defective condition in, any part or appurtenance of the Building's sanitary,
electrical, heating and air conditioning or other systems located in, or passing
through, the Sublease Premises.

         13.4 Signs, Blinds and Drapes. Except as otherwise expressly provided
in this Sublease, Sublessee shall not place any signs on the exterior of the
Building or on or in any window, public corridor or door visible from the
exterior of the Sublease Premises without the prior written approval of
Sublessor, which approval shall not be unreasonably withheld. Sublessee shall be
responsible for obtaining any required sign permits for signs it erects. No
blinds may be put on or in any window nor may any Building drapes or blinds be
removed by Sublessee. Sublessee may hang its own drapes, provided that they
shall not, without the prior written approval of Sublessor, in any way interfere
with any Building drapery or blinds or be visible from the exterior of the
Building.



                                       41
<PAGE>   48

         13.5 Estoppel Certificate. Sublessee shall at any time and from time to
time upon not less than ten (10) business days' prior notice by Landlord to
Sublessee or by Sublessor to Sublessee, execute, acknowledge and deliver to
Landlord or to Sublessor, as the case may be, a statement in writing certifying
that this Sublease is unmodified and in full force and effect (or if there have
been modifications, that the same is in full force and effect as modified and
stating the modifications), and the dates to which the Yearly Fixed Rent and
Additional Rent and other charges have been paid in advance, if any, and stating
whether or not to the best knowledge of the signer of such certificate Landlord
or Sublessor is in default in the performance of any covenant, agreement, term,
provision or condition contained in this Sublease and, if so, specifying each
such default of which the signer may have knowledge, it being intended that any
such statement delivered pursuant hereto may be relied upon by any prospective
purchaser of any interest of Landlord or Sublessor in the Building and/or Lot,
any mortgagee or prospective mortgagee, any lessee or prospective lessee
thereof, any prospective assignee of any mortgage, or any other party designated
by Landlord or Sublessor.

         13.6     Prohibited Items.  Intentionally Omitted.

         13.7A Requirements of Law - Fines and Penalties. Sublessee at its sole
expense shall comply with all laws, rules, orders and regulations of Federal,
State, County and Municipal Authorities and with any direction of any public
officer or officers (collectively, "Laws" or "Regulations") which shall impose
any duty upon Landlord, Sublessor or Sublessee with respect to and arising out
of Sublessee's use or occupancy of the Sublease Premises to the extent that the
duty to comply arises from Sublessee's particular use of the Sublease Premises
(including the Permitted Uses) and the duty to comply is not applicable to the
Building as a whole. Without limiting the generality of the foregoing, Sublessee
shall not be required to make any structural repairs or alterations applicable
to the Building as a whole. Sublessee shall have the right to contest Laws, at
its sole cost and expense, provided that (a) Sublessee is not in default
hereunder beyond applicable notice and cure periods at any time during such
contest, (b) no lien is created upon, imposed or filed against the Sublease
Premises, Building and/or Lot; and (c) no monetary obligation and/or burden is
imposed upon Sublessor or Landlord. Sublessee shall reimburse and compensate
Landlord and Sublessor for all expenditures made by, or damages or fines
sustained or incurred by, Landlord and Sublessor due to nonperformance or
noncompliance with or breach or failure to observe any term, covenant or
condition of this Sublease upon Sublessee's part to be kept, observed, performed
or complied with. If Sublessee receives notices of any violation of law,
ordinance, order or regulation applicable to the Sublease Premises, it shall
give prompt notice thereof to Landlord and Sublessor.

         13.7B Structural Items. Sublessor shall replace at its expense (except
as otherwise expressly provided in Section 5.2 hereof) during the Term all
structural items serving the Building in good, clean and safe repair, order and
condition. Structural items shall include and be limited to the foundation,
floor slabs, exterior walls, load-bearing interior walls, structural elements of
the roof, steel frame, and utility lines (specifically excluding
telecommunication and telephone equipment) and pipes serving but located outside
of the Building.



                                       42
<PAGE>   49

         13.8 Sublessee's Acts - Effects on Insurance. Sublessee shall not do or
permit to be done any act or thing upon the Sublease Premises or elsewhere in
the Building which will invalidate or be in conflict with any insurance policies
covering the Building and the fixtures and property therein described in Section
11.7 hereof and shall not do, or permit to be done, any act or thing upon the
Sublease Premises which shall subject Landlord or Sublessor to any liability or
responsibility for injury to any person or persons or to property by reason of
any business or operation being carried out on said Sublease Premises or for any
other reason. Sublessee at its own expense shall comply with all rules, orders,
regulations or requirements of the Board of Fire Underwriters or any other
similar body having jurisdiction which shall impose any duty upon Landlord,
Sublessor or Sublessee with respect to and arising out of Sublessee's use or
occupancy of the Sublease Premises to the extent that the duty to comply arises
from Sublessee's particular use of the Sublease Premises (including the
Permitted Uses) and the duty to comply is not applicable to the Building as a
whole, and shall not (i) do, or permit anything to be done, in or upon the
Sublease Premises, or bring or keep anything therein, except as now or hereafter
permitted by the Fire Department, Board of Underwriters, Fire Insurance Rating
Organization, or other authority having jurisdiction, and then only in such
quantity and manner of storage as will not increase the rate for any insurance
applicable to the Building, or (ii) use of the Sublease Premises in a manner
which shall increase such insurance rates on the Building or on property located
therein, over that applicable when Sublessee first took occupancy of the
Sublease Premises hereunder. The foregoing shall not be deemed to prohibit use
of the Sublease Premises for the Permitted Uses. If by reason of failure of
Sublessee to comply with the provisions hereof the insurance rate applicable to
any policy of insurance shall at any time thereafter be higher than it otherwise
would be, then Sublessee shall reimburse Landlord or Sublessor, as the case may
be, for that part of any insurance premiums thereafter paid by Landlord or
Sublessor, as the case may be, which shall have been charged because of such
failure by Sublessee.

         13.9 Authority. Sublessee warrants and represents that as of the date
of this Agreement of Sublease (a) it is a duly organized California corporation,
validly existing and authorized to do business in the Commonwealth of
Massachusetts, (b) it has the authority to enter into and has duly executed this
Agreement of Sublease, (c) the execution, performance and delivery by Sublessee
of this Agreement of Sublease is within the powers of Sublessee, (d) all
information provided by Sublessee to Sublessor in connection with this Agreement
of Sublease is true and accurate, (e) as of the execution of this Sublease,
Sublessee has not transferred (as defined in Article 12 hereof) this Sublease
and (f) this Sublease is the legal, valid and binding obligation of Sublessee,
enforceable against Sublessee in accordance with its terms, subject to
bankruptcy, insolvency and other limitations on creditors' rights generally and
to equitable principles.

         13.10 Miscellaneous. Sublessee shall not suffer or permit the Sublease
Premises or any fixtures, equipment or utilities therein or serving the same, to
be overloaded, damaged or defaced. Sublessee shall not permit any hole to be
drilled or made in any structural part of the Sublease Premises of the Building,
without the prior written consent of Sublessor, which consent shall not be
unreasonably withheld.



                                       43
<PAGE>   50

13A.     SUBLESSOR REPRESENTATIONS.

         Sublessor warrants and represents that as of the date of this Sublease
(a) it is a validly existing non-profit educational corporation under the laws
of the Commonwealth of Massachusetts, (b) it has the authority to enter into and
has duly executed this Agreement of Sublease, (c) the Main Lease is in full
force and effect and has a term longer than the Term (as may be extended
pursuant to Section 2.3 hereof) set forth herein, (d) the Main Lease contains
the entire agreement between Landlord and Sublessor with respect to the Sublease
Premises, (e) Sublessor is the holder of the tenant's interest under the Main
Lease, (f) Sublessor is not in and has not received notice of default under the
Main Lease and to the best of Sublessor's knowledge, Landlord is not in default
under the Main Lease, (g) there are no other buildings or improvements on the
Property (other than the Building), (h) there are no ground or underlying leases
covering all or any portion of the Building or the Property (other than the Main
Lease), (i) the Property has access to a public road, (j) applicable zoning
allows the Permitted Uses hereunder (or Landlord will obtain prior to the Term
Commencement Date necessary zoning relief for the same), (k) the execution,
performance and delivery by Sublessor of this Agreement of Sublease is within
the powers of Sublessor, (l) as of the execution of this Sublease Sublessor has
not mortgaged, pledged or otherwise encumbered any interest in the Main Lease
and Landlord has not mortgaged, pledged or otherwise encumbered any interest in
the Lot and/or Building and (m) this Sublease is the legal, valid and binding
obligation of Sublessor, enforceable against Sublessor in accordance with its
terms, subject to bankruptcy, insolvency and other limitations on creditors'
rights generally and to equitable principles. Sublessor further covenants and
agrees that (a) it will not amend the Main Lease in a manner which is adverse to
Sublessee and (b) it will comply with the terms of the Main Lease.

14.      DAMAGE BY FIRE AND CONDEMNATION


14A.     DAMAGE BY FIRE

         In the event of loss of, or damage to, the Sublease Premises or the
Building by fire or other casualty, the rights and obligations of the parties
hereto shall be as follows:

                  (a) If the Sublease Premises, or any part thereof, shall be
damaged by fire or other casualty, Sublessee shall give prompt notice thereof to
Sublessor, and Sublessor, upon receiving such notice, shall proceed promptly and
with due diligence, subject to Force Majeure Delays, to repair, or cause to be
repaired, such damage. With respect to portions of the Building outside of the
Sublease Premises that shall be damaged by fire or other casualty, Sublessor
shall proceed promptly and with due diligence, subject to Force Majeure Delay,
to repair, or to cause to be repaired, such damage after such damage occurs
except as otherwise provided herein.

                  (b) If the Sublease Premises, or any part thereof, shall be
rendered untenantable by reason of such damage, whether to the Sublease Premises
or to the 



                                       44
<PAGE>   51

Building, Yearly Fixed Rent and Additional Rent shall proportionately (i.e.,
based on rentable square footage) abate for that portion of the Sublease
Premises which is untenantable for the period from the date of such damage to
the date when such damage shall have been repaired.

                  (c) If, as a result of fire or other casualty, the whole or a
substantial part of the Building is rendered untenantable, Sublessor, within
ninety (90) days from the date of such fire or casualty, may terminate this
Sublease by notice to Sublessee, specifying a date not less than twenty (20) nor
more than forty (40) days after the giving of such notice on which the Term of
this Sublease shall terminate. If Sublessor does not so elect to terminate this
Sublease, then Sublessor shall proceed with diligence to repair the damage to
the Sublease Premises and all facilities serving the same, and the remainder of
the Main Premises which shall have occurred, and the Yearly Fixed Rent and
Additional Rent shall meanwhile proportionately abate, all as provided in
Paragraph (b) of this Article. Sublessor within one hundred twenty (120) days
after the fire or other casualty shall notify Sublessee in writing whether or
not, in its reasonable judgment, the Building and the Sublease Premises can be
restored to substantially their condition prior to such damage within twelve
(12) months of the date of the casualty. If such notification shall state that
such restoration cannot be so accomplished, then Sublessee may terminate this
Sublease within thirty (30) days from Sublessee's receipt of such notification.
Furthermore, if Sublessee does not so terminate the Sublease and if such damage
is not repaired and the Sublease Premises and the remainder of the Building
restored to substantially the same condition as they were prior to such damage
within twelve (12) months from the date of such damage, Sublessee within thirty
(30) days from the expiration of such twelve (12) month period or from the
expiration of any extension thereof by reason of Force Majeure Delays (the
"Casualty Restoration Completion Date"), may terminate this Sublease by notice
to Sublessor, specifying a date not more than forty-five (45) days after the
giving of such notice on which the term of this Sublease shall terminate. The
period within which the required repairs may be accomplished shall be extended
by the number of days lost as a result of Force Majeure Delays, provided however
that such period shall in no event be extended beyond six (6) months from the
Casualty Restoration Completion Date. Substantial part for purposes of this
Section 14A shall mean 33 1/3 % or more of the Building.

                  If Sublessee fails to terminate in accordance within the time
periods set forth herein, Sublessee shall have waived its right to terminate.

                  (d) If the Sublease Premises shall be rendered untenantable by
fire or other casualty during the last year of the Term of this Sublease,
Sublessor may terminate this Sublease effective as of the date of such fire or
other casualty upon notice to Sublessee given within sixty (60) days after such
fire or other casualty.

                  (e) With respect to Articles 14A and 14B, Sublessor shall not
be required to repair or replace any of Sublessee's trade fixtures, business
machinery, equipment, cabinet work, furniture, personal property or other
installations or improvements not originally installed by Sublessor or otherwise
required to be insured by Sublessee under the terms of this Sublease, or any
damage to the Sublease Premises or Building caused by Sublessee, or 



                                       45
<PAGE>   52

any damage to the Sublease Premises or Building not covered by condemnation
proceeds and no damages, compensation or claim shall be payable by Sublessor for
inconvenience, loss of business or annoyance arising from any repair or
restoration of any portion of the Sublease Premises or of the Building.

                  (f) The provisions of this Article shall be considered an
express agreement governing any instance of damage or destruction of the
Building or the Sublease Premises by fire or other casualty, and any law now or
hereafter in force providing for such contingency in the absence of express
agreement shall have no application.

                  (g) In the event of any termination of this Sublease pursuant
to this Article, the Term of this Sublease shall expire as of the effective
termination date as fully and completely as if such date were the date herein
originally scheduled as the Termination Date; provided that Sublessor shall
within thirty (30) days thereafter refund any prepaid Rent. Sublessee shall have
access to the Sublease Premises for a period of thirty (30) days after the date
of termination in order to remove Sublessee's personal property.

                  (h) Sublessor's architect's certificate, given in good faith,
shall be deemed conclusive of the statements therein contained and binding upon
Sublessee with respect to the performance and completion of any repair or
restoration work undertaken by Sublessor pursuant to this Article 14A or Article
14B.

14B.     CONDEMNATION

         In the event that the whole or any substantial part of the Building
shall be taken or appropriated by eminent domain or shall be condemned for any
public or quasi-public use, or (by virtue of any such taking, appropriation or
condemnation) shall suffer any damage (direct, indirect or consequential) for
which Sublessor or Sublessee shall be entitled to compensation then (and in any
such event) this Sublease and the Term hereof may be terminated at the election
of Sublessor by a notice in writing of its election so to terminate which shall
be given by Sublessor to Sublessee within ninety (90) days following the date on
which Sublessor shall have received notice of such taking, appropriation or
condemnation. In the event that a substantial part of the Sublease Premises or
of the means of access thereto or of the parking areas serving the Building, if
any (unless replaced without undue delay by substitute facilities within a
reasonable walking distance from the Building) shall be so taken, appropriated
or condemned so as to substantially interfere with the use of the Sublease
Premises, then this Sublease and the term hereof may be terminated at the
election of Sublessee by a notice in writing of its election so to terminate
which shall be given by Sublessee to Sublessor within sixty (60) days following
the date on which Sublessee shall have received notice of such taking,
appropriation or condemnation. Substantial part for purposes of this Section 14B
shall mean 40% or more of the Building.

                  Upon giving of any such notice of termination (either by
Sublessor or Sublessee), this Lease and the Term hereof shall terminate as of
the date on which Sublessee shall be required to vacate any part of the Sublease
Premises or shall be deprived of a substantial part of the means of access
thereto. In the event of any such termination, this 



                                       46
<PAGE>   53

Sublease and the Term hereof shall expire as of the effective termination date
as fully and completely as if such date were the date herein originally
scheduled as the Termination Date. If neither party elects to terminate,
Sublessor will with reasonable diligence and at Sublessor's expense, restore the
remainder of the Sublease Premises and Building, or the remainder of the means
of access and parking, to substantially the same condition as practicable
obtained prior to such taking, appropriation or condemnation in which event a
just proportion of the Yearly Fixed Rent and Additional Rent, according to the
nature and extent of the taking, appropriation or condemnation and the resultant
injury sustained by the Sublease Premises and the means of access thereto, shall
be abated until what remains of the Sublease Premises and the means of access
thereto shall have been restored as fully as may be for permanent use and
occupation by Sublessee hereunder. Except for any separate award specifically
reimbursing Sublessee for moving or relocation expenses and Sublessee's personal
property, equipment and trade fixtures, there are expressly reserved to
Sublessor all rights to compensation and damages created, accrued or accruing by
reason of any such taking, appropriation or condemnation, in implementation and
in confirmation of which Sublessee does hereby acknowledge that Sublessor shall
be entitled to receive and retain all such compensation and damages, grants to
Sublessor all and whatever rights (if any) Sublessee may have to such
compensation and damages, and agrees to execute and deliver all and whatever
further instruments of assignment with respect thereto as Sublessor may from
time to time reasonably request. In the event of any taking of the Sublease
Premises or any part thereof for temporary use, (i) this Sublease shall be and
remain unaffected thereby, and (ii) Sublessee shall be entitled to receive for
itself any award made for such use, provided, that if any taking is for a period
extending beyond the Term of this Sublease, such award shall be apportioned
between Sublessor and Sublessee as of the Termination Date.

15.      DEFAULT AND ENFORCEMENT

         15.1 Conditions of Limitation - Re-entry - Termination. This Lease and
the herein term and estate are upon the condition that if:

         (a) Sublessee shall fail to perform or observe any of Sublessee's
covenants herein beyond the applicable grace period set forth herein consisting
of the payment when due of Yearly Fixed Rent, Additional Rent, Additional Rent
for Taxes, utility expenses, Parking Rent, and/or all other additional rent; or
(b) Sublessee or Guarantor shall be involved in financial difficulties as
evidenced by an admission in writing by Sublessee or Guarantor of its inability
to pay its debts generally as they become due, or by the making or offering to
make a composition of its debts with its creditors; or (c) Sublessee or
Guarantor shall make an assignment or trust mortgage, or other conveyance or
transfer of like nature, of all or a substantial part of its property for the
benefit of its creditors; or (d) the leasehold hereby created shall be taken on
execution or by other process of law and shall not be revested in Sublessee
within sixty (60) days thereafter; or (e) a receiver, sequester, trustee or
similar officer shall be appointed by a court of competent jurisdiction to take
charge of all or a substantial part of Sublessee's property or Guarantor's
property and such appointment shall not be vacated, revoked, terminated or
stayed within sixty (60) days thereafter; or (f) any proceeding shall be
instituted by or against Sublessee or Guarantor pursuant to any of the
provisions of any Act of Congress or State law relating to bankruptcy,
reorganization, 



                                       47
<PAGE>   54

arrangements, compositions or other relief from creditors, and, in the case of
any such proceeding instituted against it or Guarantor, if Sublessee or
Guarantor shall fail to have such proceeding dismissed, stayed or vacated within
thirty (30) days or if Sublessee or Guarantor is adjudged bankrupt or insolvent
as a result of any such proceeding; or (g) any event shall occur or any
contingency shall arise whereby this Sublease, or the term and estate thereby
created, would (by operation of law or otherwise) devolve upon or pass to any
person, firm or corporation other than Sublessee, except as expressly permitted
under Article 12 hereof; or (h) Sublessee shall fail to maintain the insurance
set forth in Section 11.1 hereof; or (i) Sublessee shall grant an interest,
assign, mortgage, pledge, encumber or otherwise transfer (whether voluntarily or
by operation of law) the Sublease, the Sublease Premises or any portion thereof
in violation of Article 12 hereof; or (j) Sublessee shall fail after five (5)
business days notice to execute, acknowledge or deliver to Landlord or to
Sublessor, as the case may be, the statements or estoppel certificates required
in Section 13.5 hereof in addition to the time period already set forth in
Section 13.5 hereof; or (k) Sublessee shall fail to deliver the Inventory
Statements pursuant to the provisions of Section 4.6 hereof within ten (10)
business days after notice or Sublessee shall fail to comply with any other
provisions of Section 4.6 hereof; or (l) Sublessee shall fail after (5) business
days notice to deliver the agreements required by Landlord or Sublessor as set
forth in Section 26.12 hereof in addition to the time period already set forth
in Section 26.12 hereof; or (m) Sublessee shall fail to comply with, perform or
observe any other covenant set forth herein (any of the foregoing, an "Event of
Default"). Sublessor may, in a manner consistent with applicable law,
immediately or at any time thereafter, without further demand or notice, enter
into and upon the Sublease Premises (or any part thereof in the name of the
whole), and thereupon (and without prejudice to any remedies which might
otherwise be available for arrears of Rent or other charges due hereunder or
preceding breach of covenant and without prejudice to Sublessee's liability for
damages as hereinafter stated), upon such entry, this Sublease shall terminate.
The words "re-entry" and "re-enter" as used in this Lease are not restricted to
their technical legal meaning.

         15.2 Damages - Assignment for Benefit of Creditors. For the more
effectual securing by Sublessor of the Yearly Fixed Rent, Additional Rent and
other charges and payments reserved hereunder, it is agreed as a further
condition of this Lease that if at any time Sublessee shall make an assignment
of its property for the benefit of its creditors under the terms of which the
debts provable by its creditors shall be debts provable against the estate of
insolvent debtors either under the laws of the Commonwealth of Massachusetts or
under some law or laws other than the Bankruptcy Act as now or hereafter
enacted, then and in any such case the same shall constitute a breach of this
Lease, and the term and estate hereby created shall terminate ipso facto,
without entry or other action by Sublessor; and notwithstanding any other
provisions of this Lease, Sublessor shall forthwith upon such termination,
without prejudice to any remedies which might otherwise be available for arrears
of Yearly Fixed Rent, Additional Rent or other charges due hereunder or
preceding breach of this Lease, be ipso facto entitled to recover as liquidated
damages the sum of (a) the amount by which, at the time of such termination of
this Lease, (i) the aggregate of the Yearly Fixed Rent and Additional Rent
projected over the period commencing with such termination and ending with the
Termination Date stated in Section 2.1 exceeds (ii) the 



                                       48
<PAGE>   55

aggregate projected rental value of the Sublease Premises for such period and
(b) in view of the uncertainty of prompt re-letting and the expense entailed in
re-letting the Sublease Premises, an amount equal to the Yearly Fixed Rent and
Additional Rent payable for and in respect of the calendar year next preceding
the date of termination, as aforesaid. Upon such termination and to the extent
permitted by law, Sublessor may immediately or at any time thereafter, without
demand or notice, enter into or upon the Sublease Premises (or any part thereof
in the name of the whole), and (without being taken or deemed to be guilty of
any manner of trespass or conversion, and without being liable to indictment,
prosecution or damages thereof) may expel Sublessee and those claiming under
Sublessee from the Sublease Premises and remove therefrom the effects of
Sublessee and those claiming under Sublessee.

         15.3 Damages - Termination. Upon the termination of this Sublease under
the provisions of this Article, and except as herein above in Section 15.2
otherwise provided, Sublessee shall pay to Sublessor the Yearly Fixed Rent and
Additional Rent payable by Sublessee to Sublessor up to the time of such
termination, and all unpaid interest, shall continue to be liable for any
preceding breach of covenant, and in addition, shall pay to Sublessor as
damages, at the election of Sublessor either:

(a) the amount by which, at the time of the termination of this Sublease (or at
any time thereafter if Sublessor shall have initially elected damages under
Subparagraph (b), below), (i) the aggregate of the Yearly Fixed Rent and
Additional Rent projected over the period commencing with such time and ending
on the originally-scheduled Termination Date as stated in Section 2.1 or Section
2.3 (discounted to net present value using a 7% discount rate) exceeds (ii) the
aggregate projected fair market rental value of the Sublease Premises for such
period (discounted to net present value using a 7% discount rate), or,

(b) amounts equal to the Yearly Fixed Rent and Additional Rent which would have
been payable by Sublessee had this Sublease not been so terminated, payable upon
the due dates therefor specified herein following such termination and until the
originally-scheduled Termination Date as specified in Section 2.1, provided,
however, if Sublessor shall re-let the Sublease Premises during such period,
that Sublessor shall credit Sublessee with the net rents received by Sublessor
from such re-letting, such net rents to be determined by first deducting from
the gross rents as and when received by Sublessor from such re-letting the
expenses incurred or paid by Sublessor in terminating this Sublease, as well as
the expenses of reletting, including altering and preparing the Sublease
Premises for new tenants, brokers' commissions, and all other similar and
dissimilar expense properly chargeable against the Sublease Premises and the
rental therefrom, it being understood that any such re-letting may be for a
period equal to or shorter or longer than the remaining term of this Sublease;
and provided, further, that (i) in no event shall Sublessee be entitled to
receive any excess of such net rents over the sums payable by Sublessee to
Sublessor hereunder and (ii) in no event shall Sublessee be entitled in any suit
for the collection of damages pursuant to this Subparagraph (b) to a credit in
respect of any net rents from a re-letting except to the extent that such net
rents are actually received by Sublessor prior to the commencement of such suit.
If the Sublease Premises or any part thereof should be re-let in combination
with other space, then proper apportionment on a square foot area basis shall be
made of the Yearly 



                                       49
<PAGE>   56

Fixed Rent and Additional Rent received from such re-letting and of the expenses
of re-letting.

         Suit(s) for the recovery of such damages, or any installments thereof,
may be brought by Sublessor from time to time at its election, and nothing
contained herein shall be deemed to require Sublessor to postpone suit until the
date when the Term of this Sublease would have expired it if it had not been
terminated hereunder.

         Nothing herein contained shall be construed as limiting or precluding
the recovery by Sublessor against Sublessee of any sums or damages to which, in
addition to the damages particularly provided above, Sublessor may lawfully be
entitled by reason of any default hereunder on the part of Sublessee.

         15.4 Fees and Expenses. If Sublessee shall default in the performance
of any covenant on Sublessee's part to be performed as in this Sublease
contained, Sublessor may immediately, or at any time thereafter, subject (except
in case of emergency) to notice and expiration of any applicable grace period
which may be contained herein, perform the same for the account of Sublessee. If
Sublessor at any time is compelled to pay or elects to pay any sum of money, or
do any act which will require the payment of any sum or money, by reason of the
failure of Sublessee to comply with any provision hereof, or if Sublessor is
compelled to or does incur any expense, including, without limitation,
reasonable attorneys' fees, in instituting, prosecuting and/or defending any
action or proceeding instituted by reason of any default of Sublessee hereunder
beyond notice and the applicable cure period, Sublessee shall on demand pay to
Sublessor by way of reimbursement the sum or sums so paid by Sublessor with all
interest, costs and damages. Without limiting the generality of the foregoing,
any Yearly Fixed Rent and Additional Rent which is more than ten days in arrears
shall bear interest from the due date at the rate of 18% per annum.

         15.5 Sublessor's Remedies Not Exclusive. The specified remedies to
which Sublessor may resort hereunder are cumulative and are not intended to be
exclusive of any remedies or means of redress to which Sublessor may at any time
be lawfully entitled, and Sublessor may invoke any remedy (including, without
limitation, the remedy of specific performance) allowed at law or in equity as
if specific remedies were not herein provided for.

         15.6 Grace Period. Notwithstanding anything to the contrary in this
Article contained, Sublessor agrees not to take any action to terminate this
Sublease and Sublessee shall not be deemed in default under this Sublease
(except as otherwise set forth in Section 15.4 in cases of emergency) (a) in the
case of default by Sublessee as set forth in Section 15.1(a) in the payment when
due of Yearly Fixed Rent, Additional Rent, Additional Rent for Taxes, utility
expenses, Parking Rent, and/or all other additional rent, if Sublessee shall
cure such default within ten (10) days after written notice thereof given by
Sublessor to Sublessee, or (b) in the case of default by Sublessee in the
performance of any covenant as set forth in Section 15.1(m), if Sublessee shall
cure such default within a period of thirty (30) days after written notice
thereof given by Sublessor to Sublessee (except where the nature of the default
is such that remedial action should appropriately take place sooner, as



                                       50
<PAGE>   57

indicated in such written notice), or with respect to covenants other than to
pay a sum of money within such additional period as may reasonably be required
to cure such default if (because of governmental restrictions or any other cause
beyond the reasonable control of Sublessee) the default is of such a nature that
it cannot be cured within such thirty (30) day period, provided, however, that
there shall be no extension of time beyond such thirty (30) day period for the
curing of any such default unless, not more than ten days after the receipt of
the notice of default, Sublessee in writing (i) shall specify the cause on
account of which the default cannot be cured during such period and shall advise
Sublessor of its intention to institute all steps necessary to cure the default
and (ii) shall as soon as may be reasonable duly institute and thereafter
diligently prosecute to completion all steps necessary to cure such default. All
other defaults as set forth in Section 15.1 shall have only those notice and
cure periods, if any, as set forth in Section 15.1 hereof. Notwithstanding
anything to the contrary contained herein, Sublessor shall not be required to
give more than two (2) notices of monetary default in the payment of Yearly
Fixed Rent, Additional Rent, Additional Rent for Taxes, utility expenses,
Parking Rent, and/or all other additional rent, in any lease year; thereafter
any such monetary default shall be automatic without the need for further
notice.

16.      END OF TERM - ABANDONED PROPERTY; HOLDOVER

         Upon the expiration or other termination of the Term of this Sublease,
Sublessee shall peaceably quit and surrender to Sublessor the Sublease Premises
and all alterations and additions thereto which Sublessee is not entitled or
required to remove under the provisions of this Sublease, broom-clean, in good
order, repair and condition (to the extent of Sublessee's repair and maintenance
obligations under this Sublease) excepting only reasonable use and wear and tear
and damage by fire or other casualty for which, under other provisions of this
Sublease, Sublessee has no responsibility of repair or restoration. Sublessee's
obligation to observe or perform this covenant shall survive the expiration or
other termination of the Term of this Sublease. If the last day of the Term of
this Sublease or any renewal thereof falls on a day other than a Business Day,
this Sublease shall expire on the Business Day immediately preceding.

         Any personal property in which Sublessee has an interest which shall
remain in the Building or on the Sublease Premises after the expiration or
termination of the Term of this Sublease shall be conclusively deemed to have
been abandoned, and may be disposed of in such manner as Sublessor may see fit.
Notwithstanding the foregoing, Sublessee will, upon request of Sublessor made
not later than 30 days after the expiration or termination of the Term hereof,
promptly remove from the Building any personal property or, if any part thereof
shall be sold, then Sublessor may receive and retain the proceeds of such sale
and apply the same, at its option, against the expenses of the sale, the cost of
moving and storage, any arrears of Rent payable hereunder by Sublessee to
Sublessor and any damages to which Sublessor may be entitled under Article 15
hereof or pursuant to law, with the balance if any, to be paid to Sublessee.

         In the event of holding over by Sublessee after expiration or other
termination of this Sublease, occupancy of the Sublease Premises subsequent to
such termination or expiration shall be that of a tenancy at sufferance and in
no event for month-to-month or year-to-year, 



                                       51
<PAGE>   58

but Sublessee shall, throughout the entire holdover period, be subject to all
the terms and provisions of this Sublease and shall pay for its use and
occupancy an amount (on a per diem basis) equal to the sum of one hundred fifty
percent (150%) of the Yearly Fixed Rent and one hundred percent (100%) of the
actual Additional Rent during the holdover period, provided if such holding over
continues for more than thirty (30) days, effective as of the thirty-first
(31st) day, the amount of such holdover rental shall increase to the sum of two
hundred percent (200%) of the Yearly Fixed Rent and one hundred percent (100%)
of the actual Additional Rent during the holdover period and in no event shall
such holdover rental be less than the fair market rental for the Sublease
Premises. No holding over by Sublessee or payments of money by Sublessee to
Sublessor after the expiration of the term of this Sublease shall be construed
to extend the Term or prevent Sublessor for recovery of immediate possession of
the Sublease Premises by summary proceedings or otherwise. In addition to the
obligation to pay the amounts set forth above during any such holdover period,
Sublessee also shall be liable to Sublessor for all damage, including any
consequential damage, which Sublessor may suffer by reason of any holding over
by Sublessee, and Sublessee shall indemnify Sublessor against any and all claims
made by any other tenant or prospective tenant against Sublessor for delay by
Sublessor in delivering possession of the Sublease Premises to such other tenant
or prospective tenant.

17.      SUBLEASE SUBORDINATE; SUBORDINATION TO AND INCORPORATION OF TERMS OF
         MAIN LEASE

         (a) This Sublease shall be subject and subordinate to any mortgage now
or hereafter placed on the Main Premises, or any portions thereof or interest
therein, provided, however, that Sublessor shall obtain a subordination,
non-disturbance and attornment agreement pursuant to Section 26.12 for the
benefit of Sublessee. This Section 17 shall be self-operative and no further
instrument of subordination shall be required.

         (b) Subject to the provisions of Sections 17 and 26.12, this Sublease
is in all respects subject and subordinate to the matters to which the Main
Lease is or shall be subordinate.

18.      QUIET ENJOYMENT

         Sublessor covenants that if, and so long as there is no uncured default
and so long as, Sublessee keeps and performs in accordance with the terms and
provisions of this Sublease each and every covenant, agreement, term, provision
and condition herein contained on the part and on behalf of Sublessee to be kept
and performed, Sublessee shall quietly and peaceably have, hold, occupy and
enjoy the Sublease Premises at all times during the Term of this Sublease from
and against the claims of all persons claiming by, through or under Sublessor
subject, nevertheless, to the covenants, agreements, terms, provision and
conditions of this Sublease.

         Without incurring any liability to Sublessee, Sublessor may (subject to
applicable restrictions imposed upon Sublessee as a consequence of its dealings
with federal governmental agencies, so long as Sublessor shall have been given
prior notice thereof) 



                                       52
<PAGE>   59

permit access to the Sublease Premises and open the same, whether or not
Sublease shall be present, upon any demand of any receiver, trustee, assignee
for the benefit of creditors, sheriff, marshal or court officer entitled to, or
reasonably purporting to be entitled to, such access for the purpose of taking
possession of, or removing Sublessee's property or for any other lawful purpose
(but this provision and any action by Sublessor hereunder shall not be deemed a
recognition by Sublessor that the person or official making such demand has any
right or interest in or to this Sublease, or in or to the Sublease Premises), or
upon demand of any representative of the fire, police, building, sanitation or
other department of the city, county, state or federal governments.

19.      ENVIRONMENTAL INDEMNITY

         (a) Notwithstanding anything to the contrary contained in this Lease,
Sublessor agrees to indemnify, defend and hold harmless Sublessee, its parents,
subsidiaries and affiliates and their respective officers, directors,
shareholders and employees, from and against any and all liabilities, losses,
damages, suits, actions, causes of action, costs, expenses (including without
limitation reasonable attorneys' fees and disbursements and court costs),
penalties, fines, demands, judgements, claims or liens (including without
limitation claims or liens imposed under any so-called "Superfund" or other
environmental legislation) arising from or in connection with (i) the presence
of those Hazardous Materials (as hereinafter defined) existing at the time of or
prior to the execution date of this Sublease (the "existing Hazardous
Materials"), and/or (ii) the generation, handling, treatment, storage, disposal,
release or discharge of Hazardous Materials on, at, under, or adjacent to the
Sublease Premises, Building or Property by or at the direction of the Sublessor.

         (b) Notwithstanding anything to the contrary contained in this Lease,
Sublessee agrees to indemnify, defend and hold harmless Sublessor, Landlord, and
their respective parent, subsidiaries and affiliates, and their respective
officers, directors, shareholders and employees, from and against any and all
liabilities, losses, damages, suits, actions causes of action, costs, expenses
(including without limitation reasonable attorneys' fees and disbursements and
court costs), penalties, fines, demands, judgements, claims or liens (including
without limitation claims or liens imposed under any so-called "Superfund" or
other environmental legislation) arising from or in connection with the
generation, handling, treatment, storage, disposal, release or discharge of
Hazardous Materials which are stored, generated or otherwise brought onto,
under, at or adjacent to the Sublease Premises, Building or Property by or at
the direction of Sublessee.

         (c) For the purposes of this Sublease, the term "Hazardous Materials"
shall include without limitation any petroleum product, any flammable, explosive
or radioactive material, or any hazardous or toxic waste, substance or material,
including without limitation substances defined as "hazardous substances,"
"solid waste" or toxic substances" under any applicable laws relating to
hazardous or toxic materials and substances, air pollution (including noise and
odors), water pollution, liquid and solid waste, pesticides, drinking water,
community and employee health, environmental land use management, stormwater,
sediment control, nuisances, radiation, wetlands, endangered species,
environmental permitting and petroleum products, which laws may include, but not
be limited to, the 


                                       53
<PAGE>   60

Federal Insecticide, Fungicide, and Rodenticide Act, as amended; the Toxic
Substance Control Act; the Clean Water Act; the National Environmental Policy
Act, as Amended; the Solid Waste Disposal Act, as amended; the Comprehensive
Environmental Response, Compensation and Liability Act of 1980, as amended by
the Superfund Amendments and Reauthorization Act of 1986; The Hazardous Material
Transportation Act, as amended; the Resource Conservation and Recovery Act, as
amended, the Clean Air Act, as amended; the Emergency Planning and Community
Right-To-Know Act, as amended; the Occupational Safety and Health Act, as
amended; comparable state laws; and all rules and regulations promulgated
pursuant to such laws and ordinances.

         (d) The party seeking indemnification under this Section (the
"Indemnified Party") shall provide prompt written notice of any third party
claim to the party from whom indemnification is sought (the "Indemnifying
Party"). The Indemnifying Party shall have the right to assume exclusive control
of the defense of such claim or at the option of the Indemnifying Party, to
settle the same. The Indemnified Party agrees to cooperate reasonably with the
Indemnifying Party in connection with the performance of the Indemnifying
Party's obligations under this Section.

         (e) Notwithstanding anything to the contrary contained in this
Sublease, with respect to the indemnification provided in this Section 19,
neither party hereto shall be liable to the other for any indirect, special,
consequential or incidental damages (including without limitation loss of
profits, loss of use or loss of goodwill) regardless of (i) the negligence
(either sole or concurrent) of either party or (ii) whether either party has
been informed of the possibility of such damages.

         (f) Sublessor and Sublessee hereby acknowledge receipt of the
Environmental Report, referred to in Exhibit G attached hereto.

         (g) This Section 19 shall survive the expiration or termination of this
Sublease.

20.      ENTIRE AGREEMENT - WAIVER - SURRENDER

         20.1 Entire Agreement. This Sublease and the Exhibits made a part
hereof contain the entire and only agreement between the parties and any and all
prior statements and representations, written and oral, including previous
correspondence and agreements between the parties hereto, are merged herein.
Sublessee acknowledges that all representations and statements upon which it
relied in executing this Sublease are contained herein and that Sublessee in no
way relied upon any other statements or representations, written or oral. Any
executory agreement hereafter made shall be ineffective to change, modify,
discharge or effect an abandonment of this Sublease in whole or in part unless
such executory agreement is in writing and signed by the party against whom
enforcement of the change, modification, discharge or abandonment is sought.
Nothing herein shall prevent the parties from agreeing to amend this Sublease
and the Exhibits made a part hereof as long as such amendment shall be in
writing and shall be duly signed by both parties.



                                       54
<PAGE>   61

         20.2 Waiver. The failure of either party to seek redress for violation,
or to insist upon the strict performance, of any covenant or condition of this
Sublease, or (in the case of Sublessor) any of the Rules and Regulations
promulgated hereunder, shall not prevent a subsequent act, which would have
originally constituted a violation, from having all the force and effect of an
original violation. The receipt by Sublessor of Rent with knowledge of the
breach of any covenant of this Sublease shall not be deemed a waiver of such
breach. The failure of Sublessor to enforce any such Rules and Regulations
against Sublessee and/or any other tenant or subtenant in the Building shall not
be deemed a waiver of any such Rules and Regulations. No provisions of this
Sublease shall be deemed to have been waived by either party unless such waiver
be in writing signed by such party. No payment by Sublessee or receipt by
Sublessor of a lesser amount than the monthly rent herein stipulated shall be
deemed to be other than on account of the stipulated Rent, nor shall any
endorsement or statement on any check or any letter accompanying any check or
payment as Rent be deemed an accord and satisfaction, and Sublessor may accept
such check or payment without prejudice to Sublessor's right to recover the
balance of such rent or pursue any other remedy in this Sublease provided.

         20.3 Surrender. No act or thing done by Sublessor during the Term
hereby demised shall be deemed an acceptance of a surrender of the Sublease
Premises, and no agreement to accept such surrender shall be valid, unless in
writing signed by Sublessor. No employee of Sublessor or of Sublessor's agents
shall have any power to accept the keys of the Sublease Premises prior to the
termination of this Sublease. The delivery of keys to any employee of Sublessor
or of Sublessor's agents shall not operate as a termination of the Sublease or a
surrender of the Sublease Premises. In the event that Sublessee at any time
desires to have Sublessor underlet the Sublease Premises for Sublessee's
account, Sublessor or Sublessor's agents are authorized to receive the keys for
such purposes without releasing Sublessee from any of the obligations under this
Sublease, and Sublessee hereby relieves Sublessor of any liability for loss of
or damage to any of Sublessee's effects in connection with such underletting.

21.      INABILITY TO PERFORM - EXCULPATORY CLAUSE

         Except as otherwise expressly provided in this Sublease, this Sublease
and the obligations of Sublessee to pay Rent hereunder and perform all other
covenants, agreements, terms, provisions and conditions hereunder on the part of
Sublessee to be performed shall in no way be affected, impaired or excused
because Sublessor is unable to fulfill any of its obligations under this
Sublease or is unable to supply or is delayed in supplying any service expressly
or impliedly to be supplied or is unable to make or is delayed in making any
repairs, replacements, additions, alterations, improvements or decorations or is
unable to supply or is delayed in supplying any equipment or fixtures if
Sublessor is prevented or delayed from doing so by reason of strikes or labor
troubles or any other similar or dissimilar cause whatsoever beyond Sublessor's
reasonable control (excluding lack of funds), including but not limited to,
governmental preemption in connection with a national emergency or by reason of
any rule, order or regulation of any department of subdivision thereof or any
governmental agency or by reason of the conditions of supply and demand which
have been or are affected by war, hostilities or other similar or dissimilar
emergency. 



                                       55
<PAGE>   62

In each instance of inability of Sublessor to perform, Sublessor shall exercise
reasonable diligence to eliminate the cause of such inability to perform.

         Sublessee shall neither assert nor seek to enforce any claim for breach
of this Sublease against any of Landlord's or Sublessor's assets other than
Sublessor's interest in the Lot and the Building of which the Sublease Premises
are a part and in the rents, issues and profits (including without limitation
net sale proceeds) thereof, and Sublessee agrees to look solely to such interest
for the satisfaction of any liability of Landlord or Sublessor under this
Sublease, it being specifically agreed that in no event shall Landlord or
Sublessor (which terms shall include, without limitation, any of the officers,
trustees, directors, partners, beneficiaries, joint venturers, members,
stockholders or other principals or representatives, disclosed or undisclosed,
of Landlord, Sublessor or any managing agent) ever be personally liable for any
such liability. Sublessee specifically agrees and acknowledges that neither
Landlord nor Sublessor shall ever be liable for any breaches of the Sublease by
Landlord or Sublessor, as the case may be, other than during the period of their
respective ownership in the Building, provided any successor of Landlord or
Sublessor, as the case may be, assumes all obligations of Landlord or Sublessor,
as the case may be, from and after the date such successor acquires title to the
Lot, Building or portion of the Building or Lot, of which the Sublease Premises
are a part. In no event shall Landlord or Sublessor ever be liable for indirect,
special, consequential or incidental damages (including without limitation loss
of profits, loss of use or loss of goodwill).

22.      BILLS AND NOTICES

         Any notice, consent, request, bill, demand, statement or communication
hereunder by either party to the other party shall be in writing and, if
received at Sublessor's or Sublessee's address, shall be deemed to have been
duly given when either (a) delivered or served personally, (b) three (3) days
after mailed in a prepaid envelope, deposited in the United States mails or (c)
one (1) day after mailed by a nationally recognized overnight delivery service,
as evidenced by the records of the courier or delivery service, addressed to the
respective party at its address as stated below or if any address for notices
shall have been duly changed as hereinafter provided, if mailed as aforesaid to
the party at such changed address. Either party may at any time change the
address for such notices, consents, requests, bills, demands, statements, or
communication by delivering or mailing, as aforesaid, to the other party a
notice stating the change and setting forth the changed address, provided such
changed address is within the United States.

         Notices for purposes of the Sublease shall be as follows:

         If to SUBLESSOR:
         Mr. William J. Gasper
         Associate Vice President for Business Affairs
         Boston University Medical Campus
         Office of Financial and Business Affairs
         715 Albany Street
         Boston, MA  02118



                                       56
<PAGE>   63

         with a copy to:
         Todd L. Klipp
         Vice President and General Counsel
         Boston University - Office of the General Counsel
         125 Bay State Road
         Boston, MA 02215

         If to SUBLESSEE:
         PRIOR TO TERM COMMENCEMENT DATE:
         James G. Stewart                     David B. Marino
         Chief Financial Officer              Executive Vice President
         Vice President, Administration       The Irving Hughes Group, Inc.
         CN Biosciences, Inc.                 501 West Broadway Suite 2020
         10394 Pacific Center Court           San Diego, CA  92101
         San Diego, CA  92121

         With a copy to:
         Peter H. Jakes, Esquire
         Wilkie Farr & Gallagher
         787 7th Avenue
         New York, NY  10019






         IF AFTER TERM COMMENCEMENT DATE:
         James G. Stewart                     Calbiochem-Novabiochem Corporation
         Chief Financial Officer              c/o Oncogene Research Products
         Vice President, Administration       650 Albany Street
         CN Biosciences, Inc.                 Boston, MA  02118
         10394 Pacific Center Court           Attention:  General Manager
         San Diego, CA  92121

         With a copy to:
         Peter H. Jakes, Esquire
         Wilkie Farr & Gallagher
         787 7th Avenue
         New York, NY  10019

         All bills and statements for reimbursement or other payments or charges
due from Sublessee to Sublessor hereunder shall be due and payable in full
thirty (30) days, unless herein otherwise provided, after submission thereof by
Sublessor to Sublessee. Sublessee's failure to make timely payment of any
amounts indicated by such bills and statements, 



                                       57
<PAGE>   64

whether for work done by Sublessor at Sublessee's request, reimbursement
provided for by this Sublease or for any other sums properly owing by Sublessee
to Sublessor, shall be treated as default in the payment of Rent, in which event
Sublessor shall have all rights and remedies provided in this Sublease for
nonpayment of Rent.

         Sublessee hereby covenants that, prior to the filing of any suit for an
alleged default by Sublessor hereunder, it shall give Landlord, Sublessor and
all mortgagees whom Sublessee has been notified in writing by Sublessor to hold
mortgages or deed of trust liens on the Property, Building or Sublease Premises
notice. Sublessee hereby covenants that Sublessor shall have thirty (30) days
after the receipt of such notice to cure any alleged default.


23.      PARTIES BOUND - SEIZIN OF TITLE

         The covenants, agreements, terms, provisions and conditions of this
Sublease shall bind and benefit the successors and assigns of the parties hereto
with the same effect as if mentioned in each instance where a party hereto is
named or referred to, except that no violation of the provisions of this Article
shall not be construed as modifying the conditions of limitation contained in
Article 15 hereof.

24.      SUBLESSEE EFFORTS REGARDING MINORITY PARTICIPATION

         Sublessee shall comply with applicable federal, state and municipal
laws including without limitation all requirements of the First Source
Agreement, a copy of which is attached hereto as Exhibit H, as they pertain to
Sublessee's use and occupancy of the Sublease Premises. In furtherance of the
foregoing, to the extent required under such laws, Sublessee agrees to use
reasonable efforts to cooperate with Sublessor and Landlord to hire and train
minority and female workers from the residential area of the City of Boston of
which the Building is a part in connection with Sublessee's activities on the
Sublease Premises. Sublessee further agrees, to the extent required under such
laws, to cooperate with Sublessor and Landlord to provide opportunities for
minority, female and business enterprises based in the area of the City of
Boston in which the Building is located when purchasing supplies and equipment.
Sublessor and Landlord agrees to assist Sublessee in maximizing opportunities
for the minority, female and neighborhood resident labor forces and business
communities by identifying such job candidates and businesses with which
Sublessee may choose to do business. Sublessee acknowledges that it has an
affirmative action policy in accordance with applicable federal, state and
municipal laws and agrees that it will adhere to such policy in connection with
its use of the Sublease Premises.

25.      FIRST RIGHT OF REFUSAL

         Subject to the provisions of Section 12 hereof, during the Initial
Term, if Sublessor is negotiating a lease with a third party for either any
remaining space on the second floor and/or any space on the third floor ("First
Right of Refusal Space"), and Sublessor receives a bona fide offer from a third
party ("third party offer") with respect to any portion of the 



                                       58
<PAGE>   65

First Right of Refusal Space, Sublessor will make a proposal to Sublessee for
such space on the same terms and conditions as set forth in the third party
offer, provided, however, that the rights of Sublessee under this Section 25 are
exercisable only (i) after the applicable Right of First Refusal Space has been
initially leased by Sublessor to a third party, and (ii) if the Sublessee is not
in default hereunder beyond applicable notice and cure periods at the time it
exercises such right and at the time it enters into a lease for the First Right
of Refusal Space. Sublessee shall have seven (7) days from the date upon which
Sublessee receives such notification from Sublessor regarding the third party
offer, together with a copy of such offer, to respond to the same. If Sublessee
fails to respond to Sublessor within the aforesaid time, Sublessor will assume
that Sublessee has no desire to lease such space and Sublessee will have waived
any further rights to lease such space in which case Sublessor shall thereafter
be free to lease such space on any terms and conditions Sublessor elects whether
to the individual or entity named in the third party offer or to any other
individual or entity without any obligation to reoffer the First Right of
Refusal Space to Sublessee except as set forth in the next succeeding sentence.
If, however, at a later time or times during the Initial Term any portion of the
First Right of Refusal Space again becomes available or vacant and Sublessor
receives a bona fide offer from a third party (a "new third party offer"),
Sublessor shall again make a proposal to Sublessee for such space on the same
terms and conditions as set forth in any new third party offer. Sublessee shall
have seven (7) days from the date upon which Sublessee receives such
notification from Sublessor regarding the new third party offer, together with a
copy of such offer, to respond to the same. If Sublessee fails to respond to
Sublessor within the aforesaid time, Sublessor will assume that Sublessee has no
desire to lease such space and Sublessee will have waived any further rights to
lease such space in which case Sublessor shall thereafter be free to lease such
space on any terms and conditions Sublessor elects whether to the individual or
entity named in the new third party offer or to any other individual or entity
without any obligation to reoffer the First Right of Refusal Space to Sublessee
except as set forth herein. If Sublessee elects to lease such space, within
thirty (30) days after having received Sublessor's proposal, Sublessor and
Sublessee will enter into an amendment to this Sublease to incorporate such
space into the Sublease on the same terms and conditions set forth in
Sublessor's proposal.

26.      MISCELLANEOUS

         26.1 Separability. If any provision of this Sublease or portion of such
provision or the application thereof to any person or circumstance is for any
reason held invalid or unenforceable, the remainder of the Sublease (or the
remainder of such provision) and the application thereof to other persons or
circumstances shall not be affected thereby.

         26.2 Captions. The captions are inserted only as a matter of
convenience and for reference, and in no way define, limit or describe the scope
of this Sublease nor the intent of any provisions thereof

         26.3 Broker. Each party represents and warrants that it has not
directly or indirectly dealt, with respect to the subleasing of space in the
Building, with any broker or had its attention called to the Sublease Premises
or other space to let in the Building, by any broker other than The Irving
Hughes Group, Inc. (contracting with Avalon Partners as local 



                                       59
<PAGE>   66

licensed co-broker in the Commonwealth of Massachusetts) and Thompson Doyle &
Co., Inc. (the "Brokers"). The Brokers shall be paid by Sublessor under separate
agreements for services rendered in connection with this Sublease. Each party
agrees to exonerate and save harmless and indemnify the other against any claims
for a commission by any other broker, person or firm, with whom such party has
dealt in connection with the execution and delivery of this Sublease or out of
negotiations between Sublessor and Sublessee with respect to the subleasing of
other space in the Building other than the Brokers.

         26.4 Governing Law. This Sublease is made pursuant to, and shall be
governed by, and construed in accordance with, the laws of the Commonwealth of
Massachusetts.

         26.5 Time of the Essence. With respect to all time periods or dates set
forth herein, including without limitation, those set forth in Article 3 hereof,
time shall be of the essence.

         26.6 Notice of Sublease. Neither party shall record this Sublease in
the Registry of Deeds or Registry District, provided however that either party
shall at the request of the other, execute and deliver a recordable Notice of
this Sublease in the form prescribed by Chapter 183, Section 4 of the
Massachusetts General Laws.

         26.7 Relationship between Sublessor and Sublessee. Intentionally
omitted.

         26.8 Transfer. Sublessor shall have the right to transfer and assign,
in whole or in part, all of its rights and obligations hereunder and in the
Building and Property referred to herein, and in such event and upon such
transfer to and assumption by such transferee, Sublessor shall be released from
any further obligations hereunder, and Sublessee agrees to look solely to such
successor in interest of Sublessor for the performance of such obligations.
Notwithstanding anything contained herein to the contrary, prior to the Term
Commencement Date Sublessor shall not assign its rights and/or delegate its
duties under this Sublease, other than to affiliates or in connection with any
financing in connection with the Building.

         26.9 Financial Capability. Sublessee acknowledges that the financial
capability of Sublessee to perform its obligations hereunder and the financial
capability of Guarantor to perform its obligation under the Guaranty are
material to Sublessor and that Sublessor would not enter into this Sublease but
for its belief, based on its review of Sublessee's and Guarantor's financial
statements, that Sublessee and Guarantor are capable of performing such
financial obligations. Sublessee and Guarantor hereby represent, warrant and
certify to Sublessor that the financial statements previously furnished to
Sublessor were at the time given true and correct in all respects and that there
have been no material adverse subsequent changes thereto as of the date of this
Sublease.

         26.10 Notice to Mortgagee. Intentionally omitted.

         26.11 Attorneys' Fees. In the event that Sublessor should institute any
suit against Sublessee for violation of or to enforce any of the covenants or
conditions of this Sublease, 



                                       60
<PAGE>   67

or should Sublessee institute any suit against Sublessor for violation of any of
the covenants or conditions of this Sublease, or should either party intervene
in any suit in which the other is a party to enforce or protect its interest or
rights hereunder, the prevailing party in any such suit shall be entitled to all
of its reasonable costs and expenses and reasonable fees of its attorney(s) (if
and to the extent permitted by law) in connection therewith.

         26.12 Subordination, Non-Disturbance and Attornment Agreement.
Sublessor shall obtain and deliver or shall cause Landlord to obtain and deliver
to Sublessee, at Sublessor's sole cost and expense, a subordination,
non-disturbance and attornment agreement in commercially reasonable form from
time to time from those lenders or lessors having a mortgage, lien or leasehold
interest superior to this Sublease. Sublessee agrees to enter into any
commercially reasonable subordination, non-disturbance and attornment agreement
with a third-party lender which may be required by Landlord, Sublessor and any
third-party mortgagees or lien holders requesting the execution of such
documents within fifteen (15) days of any such request.

         IN WITNESS WHEREOF, Sublessor and Sublessee have caused this instrument
to be executed under seal, all as of the day and year first above written.


                                     SUBLESSOR:

                                     TRUSTEES OF BOSTON UNIVERSITY


                                     By: /s/ WILLIAM J. GASPER
                                        ----------------------------------------
                                        William J. Gasper, Assistant Treasurer

                                     SUBLESSEE:

                                     CALBIOCHEM-NOVABIOCHEM CORPORATION


                                     By: /s/ JAMES G. STEWART
                                        ----------------------------------------




                                       61
<PAGE>   68

                                                                  Execution Copy

                                    EXHIBIT A

                          LEGAL DESCRIPTION OF THE LOT


         Parcel "C" as shown on that plan entitled "Mortgage and Subdivision
Plan for University Associates in Boston, Mass. (South End District)" prepared
by Bryant Associates, Inc., scale 1" = 40', dated December, 1991 and recorded
with Suffolk County Registry of Deeds in Book 17190, Page 336; See Lot C on
attached Plan.



<PAGE>   69




     [MAP OF PARCEL "C" AS RECORDED WITH SUFFOLK COUNTY REGISTRY OF DEEDS]





<PAGE>   70

                                                                  Execution Copy


                                   EXHIBIT A-2

                              PARKING FACILITY MAP


<PAGE>   71


                           [MAP OF PARKING FACILITY]


<PAGE>   72

                                                                  Execution Copy

                                    EXHIBIT B

                              GROUND FLOOR PREMISES


The parties hereby agree to insert a final plan after the completion of the
Sublease Improvements and Base Building Work. Attached is a preliminary plan.



<PAGE>   73


               [MAP OF PRELIMINARY PLAN FOR GROUND FLOOR PREMISES]


<PAGE>   74

                                                                  Execution Copy


                                    EXHIBIT C

                              SECOND FLOOR PREMISES


The parties hereby agree to insert a final plan after the completion of the
Sublease Improvements and Base Building Work. Attached is a preliminary plan.



<PAGE>   75



              [MAP OF PRELIMINARY PLAN FOR SECOND FLOOR PREMISES]




<PAGE>   76

                                                                  Execution Copy


                                    EXHIBIT D

                        GUARANTY OF AGREEMENT OF SUBLEASE


Sublessor:                 Trustees of Boston University
                           715 Albany Street
                           Boston, MA 02118
                           Attention: Mr. William J. Gasper

Sublessee:                 Calbiochem-Novabiochem Corporation
                           a California corporation
                           650 Albany Street
                           Boston, MA  02118
                           Attention:  General Manager


Sublease Premises:         Approximately 28,446 rentable square feet located on
                           the ground and second floors of  the building (the 
                           "Building") to be located at 650 Albany Street, 
                           Boston, MA 02118

Date of Sublease:          July    , 1998

Sublease:                  Agreement of Sublease by and between Sublessor and 
                           Sublessee relating to Sublease Premises

Guarantor:                 CN Biosciences, Inc.
                           a Delaware corporation
                           10394 Pacific Center Court
                           San Diego, CA  92121
                           Attention: James G. Stewart, Chief Financial Officer

Guarantor's
Tax I.D. Number:

Date of Guaranty:          July    , 1998

Sublessee wishes to enter into that certain Sublease with Sublessor. Sublessor
is unwilling to enter into the Sublease unless Guarantor assures Sublessor of
the full performance of Sublessee's obligations under the Sublease. Guarantor is
willing to do so on the terms set forth herein.

Accordingly, in order to induce Sublessor to enter into the Sublease with
Sublessee, and for good and valuable consideration, receipt and adequacy of
which are acknowledged by Guarantor:



                                       1
<PAGE>   77



1.       Guarantor unconditionally guarantees to Sublessor, and the successors
         and assigns of Sublessor, Sublessee's full and punctual performance of
         its obligations under the Sublease, including without limitation the
         payment of Yearly Fixed Rent, Additional Rent and other charges due
         under the Sublease. Except as provided in the next sentence, Guarantor
         waives presentment for payment, demand for payment, notice of
         nonpayment or dishonor and protest and notice of protest. If Sublessee
         defaults in the performance of any of its obligations under the
         Sublease (and such default becomes an Event of Default under the
         Sublease), upon Sublessor's demand, Guarantor will perform such
         obligations.

2.       Any act of Sublessor, or the successors or assigns of Sublessor,
         consisting of a waiver of any of the terms or conditions of the
         Sublease, or the giving of any consent to any matter related to or
         thing relating to the Sublease, or the granting of any indulgences or
         extensions of time to Sublessee, may be done without notice to
         Guarantor and without affecting the obligations of Guarantor under this
         Guaranty.

3.       The obligations of Guarantor under this Guaranty will not be affected
         by Sublessor's receipt, application, or release of security given for
         the performance of Sublessee's obligations under the Sublease, nor by
         any modification of the Sublease that does not materially increase
         Guarantor's obligations under this Guaranty.

4.       The liability of Guarantor under this Guaranty will not be affected by:

         a.       the release or discharge of Sublessee from its obligations
                  under the Sublease in any creditors' receivership, bankruptcy,
                  or other comparable proceedings, or the commencement or
                  pendency of any such proceedings;

         b.       the impairment, limitation, or modification of the liability
                  of Sublessee or the estate of Sublessee in bankruptcy, or of
                  any remedy for the enforcement of Sublessee's liability under
                  the Sublease, resulting from the operation of any present or
                  future bankruptcy code or other comparable statute, or from
                  the decision in any court;

         c.       the rejection or disaffirmance of the Sublease in any such
                  proceedings;

         d.       the assignment or transfer of the Sublease or sublease of all
                  or part of the Sublease Premises described in the Sublease by
                  Sublessee;

         e.       any disability or other defense of Sublessee; or

         f.       the cessation from any cause whatsoever of the liability of
                  Sublessee under the Sublease.

5.       Until all of Sublessee' s obligations under the Sublease are fully
         performed, Guarantor:

         a.       waives any right of subrogation against Sublessee by reason of
                  any payments or acts of performance by Guarantor, in
                  compliance with the obligations of Guarantor under this
                  Guaranty;



                                       2
<PAGE>   78

         b.       waives any other right that Guarantor may have against
                  Sublessee by reason of any one or more payments or acts in
                  compliance with the obligations of Guarantor under this
                  Guaranty; and

         c.       subordinates any liability or indebtedness of Sublessee held
                  by Guarantor to the obligations including without limitation
                  indemnities of Sublessee to Sublessor under the Sublease.

6.       This Guaranty will apply to the Sublease, any extension or renewal of
         the Sublease as expressly set forth therein, any obligations,
         indemnities and representations made by Sublessee in the Sublease which
         survive the Term of the Sublease and any holdover term following the
         Term of the Sublease. The Guarantor's obligation hereunder shall
         thereafter be automatically discharged upon full performance of all of
         Sublessee's obligations, indemnities and representation under the
         Sublease.

7.       This Guaranty may not be changed, modified, discharged, or terminated
         orally or in any manner other than by an agreement in writing signed by
         Guarantor and Sublessor.

8.       Guarantor is primarily obligated under the Sublease. Sublessor may, at
         its option, proceed against Guarantor without proceeding against
         Sublessee or anyone else obligated under the Sublease or against any
         security for any of Sublessee's or Guarantor's obligations.

9.       If at any time payment of any rent or other amounts made by Sublessee
         under the Sublease is rescinded or must be otherwise restored or
         returned upon the insolvency, bankruptcy or reorganization of
         Sublessee, the obligations of Guarantor with respect to such payment
         shall be reinstated at such time as though such payment had never been
         made.

10.      Guarantor will pay on demand the reasonable attorneys' fees and costs
         incurred by Sublessor, or its successors and assigns, in connection
         with the enforcement of this Guaranty.

11.      Guarantor is a duly organized and validly existing corporation in good
         standing under the laws of the State of Delaware and is duly and
         legally qualified to do business as a corporation and has powers
         adequate for the execution, delivery and performance of its obligations
         under the Guaranty and for carrying on the business conducted by it.
         Guarantor has taken all necessary corporate action required to make the
         Guaranty the legal, valid and binding obligations they purport to be.
         This Guaranty has been duly executed and delivered by or on behalf of
         the Guarantor pursuant to authority legally adequate therefor, and the
         Guaranty is in full force and effect and is a legal, valid and binding
         obligation of the Guarantor and, subject to applicable bankruptcy,
         reorganization, insolvency, moratorium or similar laws affecting the
         enforcement of creditors' rights generally, and general equitable
         principles, is enforceable against Guarantor in accordance with its
         terms.



                                       3
<PAGE>   79

12.      This Guaranty shall bind the successors and assigns of Guarantor and
         this Guaranty shall inure to the benefit of Sublessor, and its
         successors and assigns.

13.      TO THE FULLEST EXTENT PERMITTED BY LAW, GUARANTOR WAIVES ALL RIGHT TO A
         TRIAL BY JURY IN ANY ACTION RELATED TO THIS GUARANTY.

14.      Any notice, consent, request, bill, demand, statement or communication
         hereunder by either party to the other party shall be in writing and,
         if received at Sublessor's or Guarantor's address, shall be deemed to
         have been duly given when either (a) delivered or served personally,
         (b) three (3) days after mailed in a prepaid envelope, deposited in the
         United States mails or (c) one (1) day after mailed by a nationally
         recognized overnight delivery service, as evidenced by the records of
         the courier or delivery service, addressed to the respective party at
         its address as stated below or if any address for notices shall have
         been duly changed as hereinafter provided, if mailed as aforesaid to
         the party at such changed address. Either party may at any time change
         the address for such notices, consents, requests, bills, demands,
         statements, or communication by delivering or mailing, as aforesaid, to
         the other party a notice stating the change and setting forth the
         changed address, provided such changed address is within the United
         States.

         Notices for purposes of this Guaranty shall be as follows:

                  If to Sublessor:

                  Mr. William J. Gasper
                  Associate Vice President for Business Affairs
                  Boston University Medical Campus
                  Office of Financial and Business Affairs
                  715 Albany Street
                  Boston, MA  02118

                  with a copy to:

                  Todd L. Klipp
                  Vice President and General Counsel
                  Boston University - Office of the General Counsel
                  125 Bay State Road
                  Boston, MA 02215




                                       4
<PAGE>   80

                  If to Guarantor:

                  CN Biosciences, Inc.
                  10394 Pacific Center Court
                  San Diego, CA  92121
                  Attention: James G. Stewart, Chief Financial Officer

                  with a copy to:

                  Peter H. Jakes, Esquire
                  Wilkie Farr & Gallagher
                  787 7th Avenue
                  New York, NY  10019

         Either Sublessor or Guarantor may add additional addresses or change
         its address for purposes of receipt of any such communication by giving
         prior written notice of such change to the other party in the manner
         prescribed above.

15.      As the Sublease Premises are located in Boston, Massachusetts,
         Guarantor agrees that its address for service of process is the address
         of the Sublease Premises or alternatively, with the Secretary of State
         of the Commonwealth of Massachusetts. In any cause of action arising
         out of or in connection with the Sublease Premises and the terms of the
         Sublease and this Guaranty, Guarantor hereby submits itself to the
         jurisdiction of any state or federal court in Massachusetts and agrees
         that any such cause of action shall be governed by the laws of the
         Commonwealth of Massachusetts and further agrees that any such cause of
         action prosecuted by Guarantor shall only be brought in state or
         federal courts in Massachusetts. The Sublease, this Guaranty and the
         rights and obligations of the parties hereto shall be construed and
         enforced in accordance with the laws of the Commonwealth of
         Massachusetts.


Guarantor has executed this Guaranty under seal as of the day and year first
above written.


                                      GUARANTOR:

                                      CN BIOSCIENCES, INC.


Witness: ________________________     By:______________________________
                                      Its:_____________________________
Print Name:______________________     Print Name:______________________
                                      Hereunto duly authorized



                                       5
<PAGE>   81


                                    EXHIBIT E

                   CONFIRMATION OF TERM COMMENCEMENT DATE AND
                             RENTABLE SQUARE FOOTAGE


         Reference is made to that certain Agreement of Sublease dated July ___,
1998 (the "Sublease") by and between CALBIOCHEM - NOVABIOCHEM CORPORATION, a
California corporation (the "Sublessee") and the TRUSTEES OF BOSTON UNIVERSITY,
a Massachusetts non-profit educational corporation (the "Sublessor"), for
certain space in the Building located at 650 Albany Street, Boston,
Massachusetts 02118 (the "Sublease Premises").

         In accordance with the terms and provisions of the above-referenced
Sublease, Sublessee and Sublessor hereby confirm the following:

         1. The Term Commencement Date of the Sublease is ___________ ____,
            1998.

         2. A. The rentable square footage of the Sublease Premises is _______
               square feet.

            B. The rentable square footage of the Main Premises is ________ 
               square feet.

            C. The rentable square footage of the Building is ________ square 
               feet.


         Agreed and Accepted:

         CALBIOCHEM - NOVABIOCHEM CORPORATION

         By:______________________________

         Title:___________________________

         Date:____________________________


         TRUSTEES OF BOSTON UNIVERSITY

         By:______________________________

         Title:___________________________

         Date:____________________________



<PAGE>   82

                                    EXHIBIT F

                         TURN-KEY WORK LETTER AGREEMENT

         This Exhibit is attached to and made a part of the Agreement of
Sublease dated July __, 1998 (the "Sublease"), by and between the Trustees of
Boston University ("Sublessor"), and Calbiochem-Novabiochem
Corporation("Sublessee") for space in the Building to be located at 650 Albany
Street.

         1. Sublessor shall perform improvements to the Sublease Premises in
accordance with the Complete Plans prepared by Sublessee and mutually approved
by Sublessor and Sublessee in accordance with the terms of Section 3.1 of the
Sublease (collectively referred to as the "Plans"). The improvements to be
performed by Sublessor in accordance with the Plans are hereinafter referred to
as the "Sublease Improvements." Except as specified on the Plans to the
contrary, the Sublease Improvements shall be performed using Building Standard
materials and Building Standard amounts and quantities of materials. Sublessee
shall work with Sublessor in good faith to select colors of carpet, paint, wood
stain and other items of finishes that are not specifically described on the
space plans prepared by Sublessee. Sublessor shall enter into a direct contract
for the Sublease Improvements with a general contractor selected by Sublessor
pursuant to Section 3.1 of the Sublease.

         2. If, after the Plans have been approved by both Sublessor and
Sublessee, Sublessee shall request any revisions to the Plans, Sublessee shall
have such revisions prepared at Sublessee's sole cost and expense (subject to
reimbursement out of Tenant Allowance). After completion of the revisions and
Sublessor's receipt of the revised Plans, Sublessor shall notify Sublessee in
writing of the increased cost in the Sublease Improvements, if any, resulting
from such revisions to the Plans. Sublessee shall, within five (5) business
days, notify Sublessor in writing whether it desires to proceed with such
revisions. In the absence of such written authorization, Sublessor shall have
the option to continue work on the Sublease Premises disregarding the requested
revision. Sublessee shall be responsible for any actual Delay in completion of
the Sublease Premises resulting from any revision to the Plans that is requested
by Sublessee. In the event such revisions result in an increase in the cost of
Sublease Improvements, such increased costs shall be payable by Sublessee within
thirty (30) days after Sublessee's receipt of evidence of such costs (to the
extent the Tenant Allowance is exhausted). Notwithstanding anything herein to
the contrary, all revisions to the Plans shall be subject to the approval of
Sublessor. Approval shall have the same meaning as set forth in Section 3.1A of
the Lease.

         3. In addition to the Sublease Improvements, Sublessor shall be
responsible for performing the Base Building Work as described in Exhibit F-2
including, without limitation, all Common Areas serving the Sublease Premises.
All Base Building Work and all costs, fees and expenses relating thereto shall
be performed at Sublessor's sole cost and expense and will not be funded out of
the Tenant Allowance. Notwithstanding the foregoing, Sublessor shall have the
right to change the plans and specifications for the Base Building Work from
time to time, provided that such changes shall not, in Sublessor's 



<PAGE>   83

reasonable judgment, reduce the overall good quality of the Base Building Work
and provided that the Building shall be a first-class building of architectural
integrity similar to the adjacent existing building in the BioSquare Project.

         4. Notwithstanding anything herein to the contrary, it is agreed that
Sublessor shall be responsible for performing the Sublease Improvements and Base
Building Work in compliance with all Laws governing construction of the Sublease
Improvements and Base Building area (including without limitation, applicable
building codes and applicable provisions of the Americans With Disabilities
Act).

         5. This Exhibit F shall not be deemed applicable to any additional
space added to the original Sublease Premises at any time or from time to time,
whether by any options under the Sublease or otherwise, or to any portion of the
original Sublease Premises or any additions to the Sublease Premises in the
event of a renewal or extension of the Original Term of this Sublease, whether
by any options under the Sublease or otherwise, unless expressly so provided in
the Sublease or any amendment or supplement to the Sublease.

         6. Sublessor, at its sole cost and expense, shall perform the Base
Building Work. All of the Sublease Improvements shall be paid for from the
Tenant Allowance, it being understood and agreed by Sublessee that all costs for
the Sublease Improvements in excess of the Tenant Allowance shall be reimbursed
by Sublessee within thirty (30)days after receipt of an invoice from Sublessor
evidencing that such costs were incurred. If Sublessee fails to pay said
invoice, Sublessor, in addition to exercising all other rights and remedies set
forth in the Sublease and Guaranty, may discontinue construction of the Sublease
Improvements and at its election, terminate the Sublease. If the cost of the
Sublease Improvements and the other Approved Sublessee Costs are less than the
Tenant Allowance, any excess Tenant Allowance shall be applied by Sublessor
pursuant to the terms of Section 3 of the Sublease.

         7. Sublessor shall, as part of the Base Building Work, install an
emergency generator in or adjacent to the Building and shall, at all times,
allow Sublessee the use of such emergency generator in an amount equal to
Sublessee's Proportionate Share. Sublessor shall deduct from the Tenant
Allowance Sublessee's Proportionate Share of Landlord's actual out-of-pocket
costs of installing and constructing the emergency generator. Sublessor shall
charge to Sublessee, as additional rent, during the Term of the Sublease,
Sublessee's Proportionate Share of those charges for the Sublessor's actual
out-of-pocket costs for the maintenance, repair and replacement of the emergency
generator and use of such emergency generator. Any invoices rendered by
Sublessor to Sublessee for the emergency generator shall be paid by Sublessee
within thirty (30) days after receipt of an invoice.

         8. If Sublessor determines that additions or upgrades are required to
the Base Building Work in order to accommodate any Sublease Improvements and (i)
the Sublease Improvement item would be cheaper to install concurrently with Base
Building Work, and (ii) Sublessee has complied with the provisions of Section
3.1 of the Sublease, Sublessee shall pay the actual cost thereof (which cost may
be deducted from the Tenant Allowance) and Sublessor shall make such addition or
upgrades concurrently with the Base Building 

                                       2

<PAGE>   84

Work, it being understood and agreed that Sublessor shall have no obligation to
make any Sublease Improvement which it does not approve. Sublessor shall have no
such obligation to accommodate any Sublessee Improvement if such improvement
will delay the construction of the Base Building Work or Sublease Improvements,
adversely affect the safety or structural integrity of the Building or otherwise
compromise the Building.

         9. Sublessor shall select contractors and subcontractors for the
Sublease Improvements pursuant to Section 3.1 of the Sublease and based on
quality, cost and availability subject to Sublessee's reasonable approval.
Without limiting the foregoing, Sublessee may reasonably disapprove Sublessor's
selection of subcontractors if the cost of the selected subcontractor is greater
than 8% of the cost of the lowest bid.

         10. Sublessee reserves the right to retain its own space planner and
interior architect, the identify of which shall be approved by Sublessor in
accordance with Section 3.1A of Sublease. The cost of Sublessee's space planner
and architect shall be paid for from the Tenant Allowance (after the cost of all
Sublease Improvements has been deducted from the Tenant Allowance) or by
Sublessee if the Tenant Allowance has been exhausted.

         11. For purposes of this Work Letter, the Sublessor's Representative
shall be:

                  Richard J. Towle
                  Vice President of Administrative Affairs
                  Boston University
                  25 Buick Street
                  Boston, MA  02215
                  Tel: (617) 353-6500
                  Fax: (617) 353-4467

                  For purposes of this Work Letter, the Sublessee's
                  Representatives shall be:

                  James G. Stewart
                  Chief Financial Officer
                  Vice President, Administration
                  CN Biosciences, Inc.
                  10394 Pacific Center Court
                  San Diego, CA  92121
                  Tel: (619) 450-5589
                  Fax: (619) 450-5522

         Such representatives may be changed from time to time upon written
notice to the other in accordance with the notice provisions of the Sublease.
Accordingly, all decisions, approvals and submissions required of Sublessor and
Sublessee by this Work Letter Agreement and the Sublease for purposes of the
construction of the Sublease Improvements shall mean the approval of the
Sublessor Representative and Sublessee Representative as indicated herein.


                                       3


<PAGE>   85



                                   EXHIBIT F-1




                             INTENTIONALLY OMITTED.


<PAGE>   86



                                   EXHIBIT F-2

                           BASE BUILDING WORK SCHEDULE


<PAGE>   87
                                                             Revised May 6, 1998
                                                             Page 1 of 7

                           BIOSQUARE II BASE BUILDING
                                  DESCRIPTION

<TABLE>
<CAPTION>
                                 DESCRIPTION                    BASE BUILDING OR
                                                                     TENANT
<S>               <C>                                           <C>
Building Design   Brick and pre-cast articulated with glass           Base
                  consistent with BioSquare CABRI.

Structural        "Floor slabs capable of supporting total            Base
                  superimposed load of 125 PSF, which includes
                  live load of 100 PSF and laboratory equipment
                  of 25 PSF".

                  Floor loading upgrades for specific tenant needs    Tenant

                  Typical floor to floor height is 13' - 6 5/8".      Base

                  Penthouse is designed for a uniform live load of    Base
                  250 PSF in order to place mechanical equipment
                  at any location.

                  Future structural modifications for tenant          Tenant
                  equipment.

Base Building     Finished first floor building lobby and egress      Base
Common Areas:     corridors. Finishes will include
                  stone/tile/terrazzo/carpet flooring, wood or tile
                  wall accents, drywall and suspended ceilings
                  and appropriate accent lighting.

                  Finished toilet rooms, janitor closets, telephone   Base
                  and electric closets, and egress stairways.

                  Bathroom finishes tile floors, wainscott. Tile      Base
                  walls to minimum 36" Above Finish Floor;
                  porcelain; fixtures, mirrors, standard HCP equip.,  
                  gyp board walls above.

                  Finished loading area with one truck bay            Base
                  equipped with leveler.

                  Finished Basement main electrical service room,     Base
                  water and gas service entry and fire pump
                  rooms.
</TABLE>
<PAGE>   88
                                                            Revised May 6, 1998
                                                            Page 2 of 7

<TABLE>
<CAPTION>

<S>                <C>                                                    <C>
                   Finished Basement main electrical service room,        Base
                   water and gas service entry and fire pump rooms.
                   
                   Supplemental or specialized mechanical equipment       Tenant
                   
                   Laboratory waste sampling pit and waste lines in       Base 
                   basement.

                   Laboratory waste neutralization equipment,             Base
                   pumps and piping in basement. Laboratory
                   Waste and Vent Risers (two (2) locations
                   per floor) capped-off at each floor
                                
Conveyance         Two (2) passenger elevators with 3,500 pound           Base
                   capacity and high quality cab finishes.
                                
                   One (1) shared service/passenger elevator with         Base
                   5,000 pound Capacity and durable cab finish.
                                
Tenant Areas       Insulated and unpainted drywall inside face of         Base 
                   exterior wall, with vapor barrier and sills.
                   
                   Partitions, ceilings, flooring, painting, other        Tenant
                   finishes, doors, millwork and all office,
                   laboratory, and animal suite buildout within
                   tenant premises.
                                
Window Treatment   Building standard blinds on all windows.               Tenant 
                                
HVAC               HVAC system will generally be an "all-air              Base
                   constant volume (occupied/unoccupied)" system
                   with base building capacities designed to
                   satisfy requirements for office and laboratory
                   space. For Laboratory Areas, system will be capable
                   of delivering 13 air changes per hour and for
                   Office areas the system will be capable of
                   cooling 4.0 watts/sq. ft. (lighting and appliance)
                   plus people and building skin heat gains.

                   Refrigeration Plant with capacity to cool 30%           Base
                   office and 70% laboratory based on net floor
                   area.
</TABLE>


<PAGE>   89
                                                             Revised May 6, 1998
                                                             Page 3 of 7

<TABLE>
<S>             <C>                                                      <C>

               Supplementary Condenser water system to cool               Base
               areas beyond Base Building system. Capped and
               valved outlets at each floor.

               Air handling equipment in floor mechanical rooms           Base
               (two (2) per floor) sized similar to refrigeration
               plant.

               Water cooled air conditioning equipment to                 Tenant
               supplement the base building and extension of
               supplementary condenser water piping on each
               floor from capped outlets on each floor to water
               cooled equipment.

               Ductwork, terminal boxes, and controls for HVAC            Base
               in lobby spaces and core areas, including toilet
               exhaust system.

               Medium pressure capped-off at mechanical room              Base
               wall and manifolded laboratory/fume hood exhaust
               ductwork capped-off at shaft wall (two (2) points
               per floor).

               Extension from perimeter of HVAC unit rooms of            Tenant
               medium pressure supply ductwork, low pressure
               ductwork and manifolded exhaust ductwork.

               All-air Constant Volume (occupied/unoccupied)             Tenant
               terminal boxes with hot water coil within tenant
               space.

               Diffusers within tenant space.                            Tenant
              
               Central computerized energy management system for         Base
               base building equipment.

               Temperature controls within tenant space, and             Tenant
               links to energy management system.

               Metering of Chilled water and hot water usage for         Tenant
               tenant area.       
</TABLE>    
<PAGE>   90
                                                             Revised May 6, 1998
                                                             Page 4 of 7



<TABLE>
<CAPTION>
<S>            <C>                                          <C>
               Manifold laboratory/fume hood exhausts,      Base
               (two (2) locations per floor), capped
               off at shaft (maximum 24 fume hoods at
               1250 C.F.M. each, per floor) and
               dedicated fume hood exhaust ducts, (two
               (2) locations per floor).

               Manifold laboratory/fume hood exhausts,      Base
               (two (2) locations per floor), capped
               off at shaft (maximum 24 fume hoods at
               1250 C.F.M. each, per floor) and
               dedicated fume hood exhaust ducts, (two
               (2) locations per floor).

               Extension of manifold exhaust and            Tenant
               dedicated fume hood exhaust ductwork
               to point of use on floor.

               Exhaust fans for dedicated fume hood         Tenant
               exhaust ducts.

Gas            Gas service to building.                     Base

Plumbing       Core toilet and janitor room fit-out.        Base

               Back-flow protection at building             Base
               service entrance.

               Dedicated cold water riser provided          Base
               at one location to 8th floor 
               (designed for 60 PSI) with valved
               and capped outlets on each floor.

               Tenant metering, submetering, and            Tenant
               backflow prevention at laboratory
               connections.

               Waste and vent risers at one location        Base
               on each floor for tie-ins from domestic
               (potable) use.

               Installation of Tenant's non-potable         Tenant
               systems in tenant area.

               Distribution of domestic cold water          Tenant
               from base building risers.

               Production and distribution of hot           Tenant
               water for tenant use.
</TABLE>
<PAGE>   91
                                                             Revised May 6, 1998
                                                             Page 5 of 7


               Kitchen, cafeteria, and specialized tenant             Tenant
               plumbing.

               Laboratory waste neutralization equipment,             Base
               pumps and piping above first floor. Laboratory
               Waste and Vent Risers (two (2) locations per
               floor) capped-off at each floor.

               Manifolds, piping, and other requirements for          Tenant
               laboratory gases, compressed air, vacuum
               systems, steam and humified air in tenant area.

Electrical     Electric Service from Boston Edison.                   Base

               Building electrical service to provide 480/277         Base
               V, 3PH, 4 wire service.

               Bus duct riser through electrical rooms at each        Base
               floor.

               Up to 12.5 watts/SF available for Tenant               Base
               lighting, receptacles and equipment.

               Additional capacity available at transformer,          Tenant
               distributed at Tenant expense.

               Service from bus duct to point-of-use including        Tenant
               metering/check metering.

               Tenant fit-up of panels, transformers,                 Tenant
               receptacles and lighting in tenant area.

               Light fixtures in tenant area to be building-          Tenant
               standard lay-in parabolic fluorescent troffer with
               electronic ballast and energy saving lamps.

               Lighting and receptacles serving core areas.           Base

               Emergency Power from a diesel driven                   Base
               emergency generator for life safety system and
               emergency lighting. Generator power
               terminates at one point per floor.




<PAGE>   92
                                                             Revised May 6, 1998
                                                             Page 6 of 7

    
                    Emergency Power from a separate diesel driven     Base
                    emergency generator sized to provide
                    emergency power for tenant usage based on 45
                    KW per floor. Generator power terminates at
                    one point per floor. Access to emergency power
                    is not included in the base rent and a separate
                    usage charge would apply.

Fire Protection     Sprinkler service entrance including fire         Base
                    department connections, alarm valve flow
                    protection, and standpipe in each stair.

                    Fire hose cabinets (if required).                 Base

                    Core and stair area sprinkler heads and piping.   Base

                    Flow control valve station in stair at each       Base
                    floor.

                    Typical floor loop for shell space. No run outs   Base
                    or sprinkler heads.

                    Revisions to the floor loop resulting from        Tenant
                    tenant improvements, including run-outs, drops,
                    and heads.

                    Special extinguishing systems.                    Tenant

Fire Alarm          Base building fire alarm system.                  Base

                    Detection and annunciation devices in core        Base
                    areas and stair entries.

                    Wiring and devices within Tenant areas.           Tenant

Telephone           Telephone riser closet and cable sleeves          Base
                    through floors.

                    Telephone and data wiring, conduits and           Tenant
                    outlets for Tenant areas.

                    Audio-visual connections and systems for          Tenant
                    Tenant areas.

    
<PAGE>   93
                                                             Revised May 6, 1998
                                                             Page 7 of 7

<TABLE>
<S>                    <C>                                          <C>
Security               Park wide security network system for        Base
                       fire alarm and access control.

                       Card access at Building entries and          Base
                       within elevators.

                       Card access and/or alarm systems into        Tenant
                       or within Tenant's premises and tie-in
                       to BioSquare security network
                       (if requested).

                       Lobby security desk with CCTV monitors,      Base
                       loading dock controls.

Roof Improvements      Building lighting protection.                Base

Signage                Building and site exterior address,          Base
                       directional, and any common identity
                       signage to BioSquare standards.

                       Building standard common area interior       Base
                       signage.

                       Exterior corporate identity sign             Tenant
                       consistent with the lease terms.

                       Signage within tenant's space.               Tenant

Roofing                EPDM system with rubber walking pads         Base
                       to all base building mechanical
                       equipment.

                       Screen wall at roof to establish visual      Base
                       and noise shield around base building
                       and base allocation of tenant rooftop
                       mechanical equipment.

                       Incremental cost to expand screen wall       Tenant
                       for additional specialized tenant
                       equipment.

Site Improvements      Perimeter sidewalks, street curbs,           Base
                       street tress, street lights and
                       furniture in accordance with BioSquare
                       design guidelines.
</TABLE>
<PAGE>   94



                                    EXHIBIT G

                              ENVIRONMENTAL REPORT


Report Prepared by Haley & Aldrich dated March 31, 1998, File Number 10666-100,
Subject: NPDES Exclusion for Construction Dewatering Proposed BioSquare II
Development, 650 Albany Street, Boston, Massachusetts; and Report Prepared by
Haley & Aldrich dated March 20, 1998, File Number 10666-100, Subject:
Preliminary Soil Pre-characterization, University Associates BioSquare II,
Boston, Massachusetts (collectively, the "Environmental Report"). Sublessor and
Sublessee hereby acknowledge that they each have a copy of the Environmental
Report and that the Environmental Report will not be attached hereto.



<PAGE>   95


                                    EXHIBIT H

                             FIRST SOURCE AGREEMENT


Cooperation Agreement for Planned Development Area No. 41, South End Technology
Square dated September 26, 1991 by and between the Boston Redevelopment
Authority and University Associates Limited Partnership and Memorandum of
Understanding dated May 20, 1992 by and between the City of Boston and
University Associates Limited Partnership (collectively, the "First Source
Agreement"). Sublessor and Sublessee hereby acknowledge receipt of said First
Source Agreement and acknowledge that a full copy of this First Source Agreement
will not be attached hereto.



<PAGE>   1

                                                                    EXHIBIT 11.1


                              CN BIOSCIENCES, INC.

                       COMPUTATION OF EARNINGS PER SHARE
                 (AMOUNTS IN THOUSANDS, EXCEPT PER SHARE DATA)


<TABLE>
<CAPTION>
                                                           THREE MONTHS ENDED        NINE MONTHS ENDED
                                                               SEPTEMBER 30             SEPTEMBER 30
                                                         ----------------------------------------------
                                                            1998         1997          1998        1997
                                                         ----------------------------------------------
<S>                                                      <C>           <C>             <C>       <C>
Net income                                                  1,272         964          3,810      2,836

Average common shares outstanding                           5,697       5,562          5,673      5,383

Net effect of dilutive common share equivalents
based on the treasury stock method                            204         266            210        310

Adjustments to reflect requirements of the
Securities and Exchange Commission (Effect
of SAB 83)                                                     --          --             --         --
                                                         ----------------------------------------------

Adjusted shares outstanding                                 5,901       5,828          5,883      5,693
                                                         ----------------------------------------------

Historical net income per share reflecting
requirements of the SEC                                   $  0.22     $  0.17        $  0.65    $  0.50
                                                         ----------------------------------------------
Effect of assumed conversion of preferred
shares from date of issuance                                   --          --             --         --
                                                         ----------------------------------------------

Adjusted shares outstanding                                 5,901       5,828          5,883      5,693
                                                         ----------------------------------------------

Pro Forma net income per share                            $  0.22     $  0.17        $  0.65    $  0.50
                                                         ----------------------------------------------
</TABLE>

<TABLE> <S> <C>

<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM THE 
REGISTRANT'S CONDENSED CONSOLIDATED FINANCIAL STATEMENTS AS OF AND FOR THE NINE 
MONTHS ENDED SEPTEMBER 30, 1998 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO
SUCH INTERIM CONSOLIDATED FINANCIAL STATEMENTS.
</LEGEND>
       
<S>                             <C>
<PERIOD-TYPE>                   9-MOS
<FISCAL-YEAR-END>                          DEC-31-1998
<PERIOD-START>                             JAN-01-1998
<PERIOD-END>                               SEP-30-1998
<CASH>                                           7,314
<SECURITIES>                                         0
<RECEIVABLES>                                    6,649
<ALLOWANCES>                                         0
<INVENTORY>                                     21,976
<CURRENT-ASSETS>                                38,897
<PP&E>                                           5,040
<DEPRECIATION>                                       0
<TOTAL-ASSETS>                                  55,116
<CURRENT-LIABILITIES>                            7,024
<BONDS>                                              0
                                0
                                          0
<COMMON>                                            57
<OTHER-SE>                                      43,641
<TOTAL-LIABILITY-AND-EQUITY>                    55,116
<SALES>                                         38,180
<TOTAL-REVENUES>                                38,180
<CGS>                                           17,148
<TOTAL-COSTS>                                   15,141
<OTHER-EXPENSES>                                     0
<LOSS-PROVISION>                                     0
<INTEREST-EXPENSE>                                   0
<INCOME-PRETAX>                                  5,891
<INCOME-TAX>                                     2,206
<INCOME-CONTINUING>                              3,810
<DISCONTINUED>                                       0
<EXTRAORDINARY>                                      0
<CHANGES>                                            0
<NET-INCOME>                                     3,811
<EPS-PRIMARY>                                     0.65
<EPS-DILUTED>                                     0.65
        

</TABLE>


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