CERUS CORP
8-K, 1999-11-12
BIOLOGICAL PRODUCTS, (NO DIAGNOSTIC SUBSTANCES)
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<PAGE>   1
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D. C. 20549

                                    FORM 8-K

                     PURSUANT TO SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934

       Date of Report (Date of earliest event reported): November 3, 1999

                                CERUS CORPORATION
             (Exact name of registrant as specified in its charter)

                                    DELAWARE
                 (State or other jurisdiction of incorporation)

                 0-21937                               68-0262011
          (Commission File No.)             (IRS Employer Identification No.)

                         2525 STANWELL DRIVE, SUITE 300
                                CONCORD, CA 94520
              (Address of principal executive offices and zip code)

       Registrant's telephone number, including area code: (925) 603-9071

                          ---------------------------
<PAGE>   2
ITEM 5. OTHER EVENTS.

      On November 3, 1999 the Board of Directors of CERUS CORPORATION (the
"Company") approved the adoption of a Share Purchase Rights Plan (the "Plan").
Terms of the Plan provide for a dividend distribution of one preferred share
purchase right (a "Right") for each outstanding share of common stock, par value
$.001 per share (the "Common Shares"), of the Company. The dividend is payable
on November 23, 1999 (the "Record Date") to the stockholders of record on that
date. Each Right entitles the registered holder to purchase from the Company one
one-hundredth of a share of Series C Junior Participating Preferred Stock, par
value $.001 per share (the "Preferred Shares"), at a price of $170 per one
one-hundredth of a Preferred Share (the "Purchase Price"), subject to
adjustment. Each one one-hundredth of a share of Preferred Shares has
designations and powers, preferences and rights, and the qualifications,
limitations and restrictions which make its value approximately equal to the
value of a Common Share. The description and terms of the Rights are set forth
in a Rights Agreement (the "Rights Agreement"), dated as of November 3, 1999
entered into between the Company and Norwest Bank Minnesota, N.A., as rights
agent (the "Rights Agent").

      Initially, the Rights will be evidenced by the stock certificates
representing the Common Shares then outstanding, and no separate Right
Certificates, as defined, will be distributed. Until the earlier to occur of (i)
the date of a public announcement that a person, entity or group of affiliated
or associated persons have acquired beneficial ownership of 15% or more of the
outstanding Common Shares (an "Acquiring Person") or (ii) 10 business days (or
such later date as may be determined by action of the Board of Directors prior
to such time as any person or entity becomes an Acquiring Person) following the
commencement of, or announcement of an intention to commence, a tender offer or
exchange offer the consummation of which would result in any person or entity
becoming an Acquiring Person (the earlier of such dates being called the
"Distribution Date"), the Rights will be evidenced, with respect to any of the
Common Share certificates outstanding as of the Record Date, by such Common
Share certificate with or without a copy of the Summary of Rights, which is
included in the Rights Agreement as Exhibit C thereof (the "Summary of Rights").

      Until the Distribution Date, the Rights will be transferable with and only
with the Common Shares. Until the Distribution Date (or earlier redemption or
expiration of the Rights), new Common Share certificates issued after the Record
Date, upon transfer or new issuance of Common Shares, will contain a notation
incorporating the Rights Agreement by reference. Until the Distribution Date (or
earlier redemption or expiration of the Rights), the surrender or transfer of
any certificates for Common Shares outstanding as of the Record Date, even
without such notation or a copy of the Summary of Rights being attached thereto,
will also constitute the transfer of the Rights associated with the Common
Shares represented by such certificate. As soon as practicable following the
Distribution Date, separate certificates evidencing the Rights ("Right
Certificates") will be mailed to holders of record of the Common Shares as of
the close of business on the Distribution Date and such separate Right
Certificates alone will evidence the Rights.


                                       1.
<PAGE>   3
      The Rights are not exercisable until the Distribution Date. The Rights
will expire on November 3, 2009 (the "Final Expiration Date"), unless the Rights
are earlier redeemed or exchanged by the Company, in each case, as described
below.

      The Purchase Price payable, and the number of Preferred Shares or other
securities or other property, upon exercise of the Rights are subject to
adjustment from time to time to prevent dilution (i) in the event of a stock
dividend on, or a subdivision, combination or reclassification of, the Preferred
Shares, (ii) upon the grant to holders of the Preferred Shares of certain rights
or warrants to subscribe for or purchase Preferred Shares at a price, or
securities convertible into Preferred Shares with a conversion price, less than
the then current market price of the Preferred Shares or (iii) upon the
distribution to holders of the Preferred Shares of evidences of indebtedness or
assets (excluding regular periodic cash dividends paid out of earnings or
retained earnings or dividends payable in Preferred Shares) or of subscription
rights or warrants (other than those referred to above). The exercise of Rights
for Preferred Shares is at all times subject to the availability of a sufficient
number of authorized but unissued Preferred Shares.

      The number of outstanding Rights and the number of one one-hundredths of a
Preferred Share issuable upon exercise of each Right are also subject to
adjustment in the event of a stock split of the Common Shares or a stock
dividend on the Common Shares payable in Common Shares or subdivisions,
consolidation or combinations of the Common Shares occurring, in any case, prior
to the Distribution Date.

      Preferred Shares purchasable upon exercise of the Rights will not be
redeemable. Each Preferred Share will be entitled to a minimum preferential
quarterly dividend payment of $1.00 but will be entitled to an aggregate
dividend of 100 times the dividend declared per Common Share. In the event of
liquidation, the holders of the Preferred Shares would be entitled to a minimum
preferential liquidation payment of $100 per share, but would be entitled to
receive an aggregate payment equal to 100 times the payment made per Common
Share. Each Preferred Share will have 100 votes, voting together with the Common
Shares. Finally, in the event of any merger, consolidation or other transaction
in which Common Shares are exchanged, each Preferred Share will be entitled to
receive 100 times the amount of consideration received per Common Share. These
rights are protected by customary anti-dilution provisions. Because of the
nature of the Preferred Shares' dividend and liquidation rights, the value of
one one-hundredth of a Preferred Share should approximate the value of one
Common Share. The Preferred Shares would rank junior to any other series of the
Company's preferred stock.

      In the event that any person or group of affiliated or associated persons
becomes an Acquiring Person, proper provision shall be made so that each holder
of a Right, other than Rights beneficially owned by the Acquiring Person and its
associates and affiliates (which will thereafter be void), will for a 60-day
period have the right to receive upon exercise that number of Common Shares
having a market value of two times the exercise price of the Right (or, if such
number of shares is not and cannot be authorized, the Company may issue
Preferred Shares, cash, debt, stock or a combination thereof in exchange for the
Rights). This right will terminate 60 days after the date on which the Rights
become nonredeemable (as described below), unless there is an injunction or
similar obstacle to exercise of the Rights, in which event this right will
terminate 60 days after the date on which the Rights again become exercisable.
In the event that


                                       2.
<PAGE>   4
any person or group of affiliated or associated persons becomes an Acquiring
Person, the Rights will no longer represent the right to purchase Preferred
Shares.

      Generally, under the Plan, an "Acquiring Person" shall not be deemed to
include (i) the Company, (ii) a subsidiary of the Company, (iii) any employee
benefit or compensation plan of the Company, (iv) any entity holding Common
Shares for or pursuant to the terms of any such employee benefit or compensation
plan or (v) an "Excluded Stockholder," as defined under the Plan. In addition,
except under limited circumstances, no person or entity shall become an
Acquiring Person as the result of the acquisition of Common Shares by the
Company which, by reducing the number of shares outstanding, increases the
proportionate number of shares beneficially owned by such person or entity to
15% or more of the Common Shares then outstanding. Baxter Healthcare Corporation
and its associates and affiliates will be an Excluded Stockholder so long as
they hold, in the aggregate, 20.1% or less of the Company's outstanding common
shares, excluding for this purpose Common Shares deemed to be owned through
Baxter's ownership of Series A Preferred Stock of the Company as a result of the
transactions contemplated by that certain Series A Preferred Stock Purchase
Agreement between Baxter and the Company dated June 30, 1998, and Series B
Preferred Stock of the Company as a result of transactions contemplated by that
certain Series B Preferred Stock Purchase Agreement between Baxter and the
Company dated June 30, 1998.

      In the event that the Company is acquired in a merger or other business
combination transaction or 50% or more of its consolidated assets or earning
power are sold to an Acquiring Person, its associates or affiliates or certain
other persons in which such persons have an interest, proper provision will be
made so that each holder of a Right will thereafter have the right to receive,
upon the exercise thereof at the then current exercise price of the Right, that
number of shares of common stock of the acquiring company which at the time of
such transaction will have a market value of two times the exercise price of the
Right.

      At any time after an Acquiring Person becomes an Acquiring Person and
prior to the acquisition by such Acquiring Person of 50% or more of the
outstanding Common Shares, the Board of Directors of the Company may exchange
the Rights (other than Rights owned by such person or group which have become
void), in whole or in part, at an exchange ratio of one Common Share, or one
one-hundredth of a Preferred Share, per Right (or, at the election of the
Company, the Company may issue cash, debt, stock or a combination thereof in
exchange for the Rights), subject to adjustment.

      With certain exceptions, no adjustment in the Purchase Price will be
required until cumulative adjustments require an adjustment of at least 1% in
such Purchase Price. No fractional Preferred Shares will be issued (other than
fractions which are integral multiples of the number of one one-hundredths of a
Preferred Share issuable upon the exercise of one Right, which may, at the
election of the Company, be evidenced by depositary receipts), and in lieu
thereof, an adjustment in cash will be made based on the market price of the
Preferred Shares on the last trading day prior to the date of exercise.

      At any time prior to the earliest of (i) the day of the first public
announcement that a person has become an Acquiring Person or (ii) the Final
Expiration Date, the Board of Directors


                                       3.
<PAGE>   5
of the Company may redeem the Rights in whole, but not in part, at a price of
$0.01 per Right (the "Redemption Price"). Following the expiration of the above
periods, the Rights become nonredeemable. Immediately upon any redemption of the
Rights, the right to exercise the Rights will terminate and the only right of
the holders of Rights will be to receive the Redemption Price.

      The terms of the Rights may be amended by the Board of Directors of the
Company without the consent of the holders of the Rights, except that from and
after such time as the rights are distributed no such amendment may adversely
affect the interest of the holders of the Rights excluding the interests of an
Acquiring Person.

      Until a Right is exercised, the holder thereof, as such, will have no
rights as a stockholder of the Company, including, without limitation, the right
to vote or to receive dividends.

      The Rights have certain anti-takeover effects. The Rights will cause
substantial dilution to a person or group that attempts to acquire the Company
on terms not approved by the Company's Board of Directors. The Rights should not
interfere with any merger or other business combination approved by the Board of
Directors since the Rights may be amended to permit such acquisition or redeemed
by the Company at $.001 per Right prior to the earliest of (i) the time that a
person or group has acquired beneficial ownership of 15% or more of the Common
Shares or (ii) the final expiration date of the rights.

ITEM 7. EXHIBITS.

<TABLE>
<S>            <C>
      4.1      Registrant's Certificate of Incorporation (including
               Certificate of Designation of Series C Junior Participating
               Preferred Stock.)

     99.1      Press Release, dated as of November 3, 1999 entitled "Cerus
               Corporation Adopts Stockholder Rights Plan."

     99.2      Rights Agreement dated as of November 3, 1999 among Cerus
               Corporation and Norwest Bank Minnesota, N.A.

     99.3      Form of Rights Certificate.
</TABLE>


                                       4.
<PAGE>   6
                                    SIGNATURE

      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.

                                          CERUS CORPORATION

Dated:  November 9, 1999                  By:   /s/ STEPHEN T. ISAACS
                                                --------------------------------
                                                STEPHEN T. ISAACS
                                                President and Chief Executive
                                                Officer


                                       5.
<PAGE>   7
                                INDEX TO EXHIBITS

<TABLE>
<S>       <C>
 4.1      Registrant's Certificate of Incorporation (including
          Certificate of Designation of Series C Junior Participating
          Preferred Stock.)

99.1      Press Release, dated as of November 3, 1999 entitled "Cerus
          Corporation Adopts Stockholder Rights Plan."

99.2      Rights Agreement dated as of November 3, 1999 among Cerus Corporation
          and Norwest Bank Minnesota, N.A.

99.3      Form of Rights Certificate.
</TABLE>


                                       6.

<PAGE>   1
                                                                     EXHIBIT 4.1

                              AMENDED AND RESTATED
                          CERTIFICATE OF INCORPORATION


        CERUS CORPORATION, a corporation organized and existing under and by
virtue of the General Corporation Law of the State of Delaware, hereby certifies
as follows:

        1. The name of the corporation is Cerus Corporation.

        2. The corporation's original Certificate of Incorporation was filed
with the Secretary of State on July 31, 1996.

        3. The Amended and Restated Certificate of Incorporation of this
corporation, in the form attached hereto as Exhibit A, has been duly adopted in
accordance with the provisions of Sections 242 and 245 of the General
Corporation Law of the State of Delaware by the Board of Directors and by the
stockholders of the corporation, and prompt written notice was duly given
pursuant to Section 228 of the General Corporation Law of the State of Delaware
to those stockholders who did not approve the Amended and Restated Certificate
of Incorporation by written consent.

        4. The Amended and Restated Certificate of Incorporation so adopted
reads in full as set forth in Exhibit A attached hereto and hereby incorporated
by reference.

        IN WITNESS WHEREOF, Cerus Corporation has caused this Amended and
Restated Certificate of Incorporation to be signed by its President and Chief
Executive Officer and attested to by its Secretary this 6th day of February,
1997.



                                        /s/ Stephen T. Isaacs
                                        -------------------------------------
                                        STEPHEN T. ISAACS
                                        President and Chief Executive Officer

ATTEST:



/s/ Lori Roll
- -------------------------------
LORI ROLL
Secretary


                                       1.


<PAGE>   2
                                    EXHIBIT A

                              AMENDED AND RESTATED
                          CERTIFICATE OF INCORPORATION
                                       OF
                                CERUS CORPORATION


                                       I.

        The name of this corporation is Cerus Corporation.


                                       II.

        The address of the registered office of the corporation in the State of
Delaware is 9 East Loockerman Street, City of Dover, County of Kent, and the
name of the registered agent of the corporation in the State of Delaware at such
address is the National Registered Agents, Inc.


                                      III.

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


                                       IV.

        A. This corporation is authorized to issue two classes of stock to be
designated, respectively, "Common Stock" and "Preferred Stock." The total number
of shares which the corporation is authorized to issue is fifty-five million
(55,000,000) shares. Fifty million (50,000,000) shares shall be Common Stock,
each having a par value of one-tenth of one cent ($.001). Five million
(5,000,000) shares shall be Preferred Stock, each having a par value of
one-tenth of one cent ($.001).

        The Preferred Stock may be issued from time to time in one or more
series. The Board of Directors is hereby authorized, by filing a certificate (a
"Preferred Stock Designation") pursuant to the Delaware General Corporation Law,
to fix or alter from time to time the designation, powers, preferences and
rights of the shares of each such series and the qualifications, limitations or
restrictions of any wholly unissued series of Preferred Stock, and to establish
from time to time the number of shares constituting any such series or any of
them; and to increase or decrease the number of shares of any series subsequent
to the issuance of shares of that series, but not below the number of shares of
such series then outstanding. In case the number of shares of any series shall
be decreased in accordance with the foregoing sentence, the shares constituting
such decrease shall resume the status that they had prior to the adoption of the
resolution originally fixing the number of shares of such series.


                                       1.


<PAGE>   3
                                       V.

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

        A.

               1. The management of the business and the conduct of the affairs
of the Corporation shall be vested in its Board of Directors. The number of
directors which shall constitute the whole Board of Directors shall be fixed
exclusively by one or more resolutions adopted by the Board of Directors.

               2. Subject to the rights of the holders of any series of
Preferred Stock to elect additional directors under specified circumstances,
following the closing of the initial public offering pursuant to an effective
registration statement under the Securities Act of 1933, as amended (the "1933
Act"), covering the offer and sale of Common Stock to the public (the "Initial
Public Offering"), the directors shall be divided into three classes designated
as Class I, Class II and Class III, respectively. Directors shall be assigned to
each class in accordance with a resolution or resolutions adopted by the Board
of Directors. At the first annual meeting of stockholders following the closing
of the Initial Public Offering, the term of office of the Class I directors
shall expire and Class I directors shall be elected for a full term of three
years. At the second annual meeting of stockholders following the closing of the
Initial Public Offering, the term of office of the Class II directors shall
expire and Class II directors shall be elected for a full term of three years.
At the third annual meeting of stockholders following the closing of the Initial
Public Offering, the term of office of the Class III directors shall expire and
Class III directors shall be entered for a full-term of three years. At each
succeeding annual meeting of stockholders, directors shall be elected for a full
term of three years to succeed the directors of the class whose terms expire at
such annual meeting.

               Notwithstanding the foregoing provisions of this Article, each
director shall serve until his successor is duly elected and qualified or until
his death, resignation or removal. No decrease in the number of directors
constituting the Board of Directors shall shorten the term of any incumbent
director.

               3. Subject to the rights of the holders of any series of
Preferred Stock, any vacancies on the Board of Directors resulting from death,
resignation, disqualification, removal or other causes and any newly created
directorships resulting from any increase in the number of directors, shall,
unless the Board of Directors determines by resolution that any such vacancies
or newly created directorships shall be filled by the stockholders, except as
otherwise provided by law, be filled only by the affirmative vote of a majority
of the directors then in office, even though less than a quorum of the Board of
Directors, and not by the stockholders. Any director elected in accordance with
the preceding sentence shall hold office for the remainder of the full term of
the director for which the vacancy was created or occurred and until such
director's successor shall have been elected and qualified.


                                       2.


<PAGE>   4
        B.

               1. Subject to paragraph (h) of Section 43 of the Bylaws, the
Bylaws may be altered or amended or new Bylaws adopted by the affirmative vote
of at least sixty-six and two-thirds percent (66-2/3%) of the voting power of
all of the then-outstanding shares of voting stock of the Corporation entitled
to vote at an election of directors (the "Voting Stock"). The Board of Directors
shall also have the power to adopt, amend, or repeal Bylaws.

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

               3. No action shall be taken by the stockholders of the
Corporation except at an annual or special meeting of stockholders called in
accordance with the Bylaws and following the closing of the Initial Public
Offering no action shall be taken by the stockholders by written consent.

               4. Advance notice of stockholder nominations for the election of
directors and of business to be brought by stockholders before any meeting of
the stockholders of the Corporation shall be given in the manner provided in the
Bylaws of the Corporation.

                                       VI.

        A. A director of the Corporation shall not be personally liable to the
Corporation or its stockholders for monetary damages for any breach of fiduciary
duty as a director, except for liability (i) for any breach of the director's
duty of loyalty to the Corporation or its stockholders, (ii) for acts or
omissions not in good faith or which involve intentional misconduct or a knowing
violation of law, (iii) under Section 174 of the Delaware General Corporation
Law, or (iv) for any transaction from which the director derived an improper
personal benefit. If the Delaware General Corporation Law is amended after
approval by the stockholders of this Article to authorize corporate action
further eliminating or limiting the personal liability of directors, then the
liability of a director shall be eliminated or limited to the fullest extent
permitted by the Delaware General Corporation Law, as so amended.

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

                                      VII.

        A. The Corporation reserves the right to amend, alter, change or repeal
any provision contained in this Certificate of Incorporation, in the manner now
or hereafter prescribed by statute, except as provided in paragraph B of this
Article VII, and all rights conferred upon the stockholders herein are granted
subject to this reservation.

        B. Notwithstanding any other provisions of this Certificate of
Incorporation or any provision of law which might otherwise permit a lesser vote
or no vote, but in addition to any affirmative vote of the holders of any
particular class or series of the Voting Stock required by law, this Certificate
of Incorporation or any Preferred Stock Designation, the affirmative vote of the
holders of at least sixty-six and two-thirds percent (66-2/3%) of the voting
power of all of the


                                       3.


<PAGE>   5
then-outstanding shares of the Voting Stock, voting together
as a single class, shall be required to alter, amend or repeal Articles V, VI
and VII.


                                       4.


<PAGE>   6


                           CERTIFICATE OF DESIGNATION
                           OF SERIES A PREFERRED STOCK
                              OF CERUS CORPORATION


        The undersigned, Stephen T. Isaacs, hereby certifies that:

        1. He is the duly elected and acting President and Secretary,
respectively, of CERUS CORPORATION, a Delaware corporation (the "Company"). The
date of filing of the Amended and Restated Certificate of Incorporation (the
"Certificate") was February 7, 1997.

        2. The Board of Directors of the Company adopted the following recitals
and resolutions as required by Section 151 of the General Company Law of the
State of Delaware at a meeting held on June 30, 1998:

                WHEREAS, the Certificate provides for a class of shares known as
        Preferred Stock, issuable from time to time in one or more series; and

                WHEREAS, the Board of Directors of the Company is authorized by
        Section A of Article IV of the Certificate and, pursuant to its
        authority as aforesaid, desires to fix the terms of the first series of
        said Preferred Stock, the number of shares constituting said series and
        the designation of said series.

                NOW, THEREFORE, BE IT RESOLVED, that the Board of Directors
        deems it advisable to adopt, and hereby adopts, the following
        Certificate of Designation of Preferences of Series A Preferred Stock of
        the Company:

               SECTION 1. DESIGNATION. Five Thousand (5,000) shares of Preferred
Stock, $0.001 par value, are designated "Series A Preferred Stock" with the
powers, preferences, rights, qualifications, limitations and restrictions
specified herein (the "Series A Preferred").

               SECTION 2. VOTING RIGHTS. The holders of shares of Series A
Preferred shall not have any voting rights, except as provided in this Section 2
and as required under the General Corporation Law of Delaware. Without first
obtaining the affirmative vote or written consent of the holders of at least a
majority of the outstanding shares of Series A Preferred, voting as a separate
class, the Company shall not effect any merger or consolidation in which the
Company is not the surviving entity, or any merger, consolidation or other
transaction in which the Company's Common Stock becomes no longer publicly
traded (a "Covered Transaction"), unless the surviving entity in the Covered
Transaction shall have provided for the benefit of the holders of Series A
Preferred contractual rights (the "Contractual Rights") to receive (i) on the
15th day following the Approval Payment Date (as hereinafter defined) or the
Termination Payment Date (as hereinafter defined), as the case may be, the
consideration that the holders of Series A Preferred would have received in the
Covered Transaction had the Series A Preferred been converted into Company
Common Stock immediately prior to the effectuation or consummation of the
Covered Transaction in accordance with the method of conversion used in Section
5(a)(1) or 5(a)(2), as the case may be, at one hundred twenty percent (120%) (in
the case of an Approval Event (as hereinafter defined)), or at one hundred
percent (100%) (in the case of


                                       1.


<PAGE>   7
a Termination Event (as hereinafter defined)) of the closing price of the
Company's Common Stock immediately prior to the Covered Transaction, (with any
securities that would have been received as part of such consideration being
adjusted for any stock splits, stock combinations and the like from the date of
the Covered Transaction to the date of the Approval Event or the Termination
Event, as the case may be) and (ii) any dividends or other distributions, or
shares issued in any reclassification, exchange or substitution of securities or
in any reorganization, merger or consolidation, that the Series A Preferred
holders would have received from the date of the Covered Transaction to the date
of the Approval Event or Termination Event, as the case may be, in respect of
the securities, if any, that holders of the Series A Preferred would have
received in the Covered Transaction as set forth in (i) above; provided that the
Contractual Rights shall be subject to a right by the surviving entity to
repurchase, and upon a Termination Event, a right of the holders of a majority
of the outstanding shares of the Series A Preferred to require the repurchase
of, the Contractual Rights in the same manner, at the same times and at the same
price as the Company's right to redeem the Series A Preferred pursuant to
Section 4 below.

               SECTION 3. LIQUIDATION RIGHTS.

                      (a) Upon any liquidation, dissolution, or winding up of
the Company, whether voluntary or involuntary, the holders of Series A Preferred
shall be entitled to be paid out of the assets of the Company, before any
payment or distribution of assets of the Company (whether capital or surplus)
shall be made to or set aside for the holders of Common Stock and after and
subordinate to any other class or series of Preferred Stock, an amount per share
of Series A Preferred equal to the "Original Issue Price." The Original Issue
Price of the Series A Preferred shall be One Thousand Dollars ($1,000.00). If,
upon any liquidation, distribution, or winding up, the assets of the Company
shall be insufficient to make payment in full under this Section 3(a) to all
holders of Series A Preferred, then such assets shall be distributed among the
holders of Series A Preferred at the time outstanding, ratably in proportion to
the full stated amounts to which they would otherwise be respectively entitled
under this Section 3(a).

                      (b) The following events shall not be considered a
liquidation, dissolution or winding up under this Section 3:

                           (1) any consolidation or merger of the Company with
or into any other corporation or other entity or person, or any other corporate
reorganization or other transaction or series of transactions resulting in a
change in ownership of the outstanding securities of the Company; or

                           (2) a sale, lease or other disposition of all or any
part of the assets of the Company.

               SECTION 4. REDEMPTION.

                      (a) Upon (i) the approval of a new drug application (NDA)
or pre-market approval (PMA) or equivalent by the United States Food and Drug
Administration under the Development, Manufacturing and Marketing Agreement
dated as of December 10, 1993 between the Company and Baxter Healthcare
Corporation, as amended from time to time (the "Platelet Agreement") or (ii) CE
Mark approval in Europe under the Platelet Agreement (either,


                                       2.


<PAGE>   8
an "Approval Event"), the Company shall have the right to redeem all or any
portion of the Series A Preferred at the Original Issue Price.

                      (b) Upon the termination for any reason of the Platelet
Agreement or upon cessation for any reason of the Cooperative Development Work
(as such term is defined in the Platelet Agreement) (either, a "Termination
Event"), the Company shall have the right, and the holders of a majority of the
outstanding shares of Series A Preferred shall have the right to require the
Company, to redeem all, but not less than all, the Series A Preferred at the
Original Issue Price.

                      (c) Immediately prior to consummation of a Covered
Transaction, the Company shall have the right to redeem all, but not less than
all, shares of Series A Preferred Stock then outstanding at the Original Issue
Price.

                      (d) In the event the Company desires to redeem the Series
A Preferred pursuant to Section 4(a), the Company shall, within ten (10) days
after the Approval Payment Date (as defined below), send a notice to the Series
A Preferred holders notifying the holders of redemption and setting forth the
number of shares of Series A Preferred to be redeemed and the total amount to be
paid for the shares of Series A Preferred being redeemed (the "Redemption
Price"). If, at the time of any redemption pursuant to Section 4(a) for less
than all of the Series A Preferred, there shall be more than one holder of the
Series A Preferred, such redemption shall be made pro rata among the holders of
the Series A Preferred in proportion to the number of shares of Series A
Preferred held by each such holder. The "Approval Payment Date" means the date
on which the Company receives payment of the amount payable to it under Section
4.3 of the Platelet Agreement

                      (e) In the event the Company or the holders of a majority
of the outstanding shares of the Series A Preferred desires to have the Series A
Preferred redeemed pursuant to Section 4(b) above, the Company or the Series A
Preferred holders shall, within ten (10) days after the Termination Payment Date
(as defined below), send a notice to the Company or the Series A Preferred
holders, as the case may be, stating that the Series A Preferred shall be
redeemed pursuant to this subsection (e). The amount to be paid for the Series A
Preferred being redeemed shall also be referred to as the "Redemption Price."
The "Termination Payment Date" means the date on which the Company receives
payment of the amount payable to it under Section 13.4 of the Platelet
Agreement.

                      (f) In the event the Company desires to have the Series A
Preferred redeemed pursuant to Section 4(c) above, the Company shall, not less
than ten (10) days before the date of consummation of the Covered Transaction,
send a notice to the Series A Preferred holders indicating that the Series A
Preferred shall be redeemed pursuant to this subsection (f). The amount to be
paid for the Series A Preferred being redeemed shall also be referred to as the
"Redemption Price."

                      (g) Within five (5) days after receipt of a redemption
notice from the Company or within five (5) days after the sending of a
redemption notice to the Company pursuant to Section 4(d), Section 4(e) or
Section 4(f) above, as the case may be, the Series A Preferred holders shall
surrender that number of Series A Preferred share certificates set forth in a
redemption notice by the Company, in the case of redemption pursuant to Section
4(a) above,


                                       3.


<PAGE>   9
or all Series A Preferred share certificates, in the case of redemption pursuant
to Section 4(b) or Section 4(c) above, at the principal executive office of the
Company, and thereupon the Redemption Price shall be payable, in cash by wire
transfer or certified check, to the order of the person whose name appears on
such certificate or certificates as the owner thereof and each surrendered
certificate shall be canceled. Notwithstanding the foregoing, the Redemption
Price payable upon a redemption in connection with a Covered Transaction will be
payable, and the share certificates for the Series A Preferred shall be
canceled, only upon consummation of the Covered Transaction. If the Company does
not have sufficient funds legally available to redeem all shares to be redeemed
pursuant to this Section 4, then it shall use those funds which are legally
available to redeem the maximum possible number of such shares pro rata among
the holders of the Series A Preferred Stock. At any time thereafter when funds
of the Company are legally available for the redemption of shares of Series A
Preferred, such funds will immediately be used to redeem the balance of the
shares which the Company has become obligated to redeem pursuant to this Section
4 but which it has not redeemed. In the event that a redemption notice is given
pursuant to Section 4(f) above in connection with an impending Covered
Transaction, and the Covered Transaction is later terminated without being
consummated, the Company will so notify the holders of the Series A Preferred
Stock, and the redemption notice and redemption will be deemed rescinded and any
tendered share certificates will be returned to the holders of the Series A
Preferred, with the same effect as if such redemption notice had not been given.

               SECTION 5. CONVERSION RIGHTS. The following provisions shall
apply with respect to the conversion of the Series A Preferred into shares of
Common Stock:

                      (a) CONVERSION.

                           (1) Subject to Section 5(a)(3) below, upon the
occurrence of an Approval Event, if a notice of redemption of the Series A
Preferred has not been sent by the Company pursuant to Section 4(d) above, each
share of Series A Preferred shall automatically be converted into that number of
fully paid and nonassessable shares of Common Stock equal to the Original Issue
Price divided by one hundred twenty percent (120%) of the average closing price
of the Common Stock, as reported in The Wall Street Journal, for the thirty (30)
trading days prior to and including the trading day immediately prior to the
Approval Event. The date on which such conversion shall occur shall be the 15th
day following the Approval Payment Date.

                           (2) Subject to Section 5(a)(3) below, upon the
occurrence of a Termination Event, if a redemption notice has not been sent by
the Company or the holder of the Series A Preferred pursuant to Section 4(e)
above, each share of Series A Preferred shall automatically be converted into
that number of fully paid and nonassessable shares of Common Stock equal to the
Original Issue Price divided by the average closing price of the Common Stock,
as reported in The Wall Street Journal, for the thirty (30) trading days
commencing with the fifteenth (15th) trading day prior to the Termination Event.
The date on which such conversion shall occur shall be the 15th day following
the Termination Payment Date.

                           (3) Notwithstanding anything contained in this
Section 5 to the contrary, the Series A Preferred shall not convert, and no
shares of Common Stock shall be issued by the Company thereby, unless and until
the pre-merger notification requirements of the Hart-Scott-Rodino Antitrust
Improvements Act of 1976, as amended (the "HSR Act"), have been complied with,
and any waiting period under the HSR Act applicable to the conversion of the


                                       4.


<PAGE>   10
Series A Preferred has expired or been terminated and any approvals required
thereunder have been obtained.

                           (4) Upon the conversion of the Series A Preferred
pursuant to this Section 5, the outstanding shares of Series A Preferred shall
be converted automatically without any further action by the holders of such
shares and whether or not the certificates representing such shares are
surrendered to the Company or its transfer agent; provided, however, that the
Company shall not be obligated to issue certificates evidencing the shares of
Common Stock issuable upon such conversion unless the certificates evidencing
such shares of Series A Preferred are either delivered to the Company or its
transfer agent as provided below, or the holder notifies the Company or its
transfer agent that such certificates have been lost, stolen or destroyed and
executes an agreement satisfactory to the Company to indemnify the Company from
any loss incurred by it in connection with such certificates. Upon the
occurrence of such automatic conversion of the Series A Preferred, the holders
of Series A Preferred shall surrender the certificates representing such shares
at the office of the Company or any transfer agent for the Series A Preferred.
Thereupon, there shall be issued and delivered to such holder promptly at such
office and in its name as shown on such surrendered certificate or certificates,
a certificate or certificates for the number of shares of Common Stock into
which the shares of Series A Preferred surrendered were convertible on the date
on which such automatic conversion occurred.

                           (5) Notwithstanding anything contained in this
Section 5 to the contrary, in the event that the approval of the Company's
stockholders is required pursuant to Rule 4460(i) of the Nasdaq Stock Market
("Rule 4460(i)") prior to the issuance of any of the shares of Common Stock
issuable upon conversion of the Series A Preferred, the Company shall obtain
such approval by the applicable conversion date under Section 5(a)(i) or 5(a)(2)
hereof. In the event such approval is not obtained by the applicable conversion
date, the Company shall, in accordance with Section 4 hereof, redeem any shares
of Series A Preferred that would be convertible into shares of Common Stock in
excess of the limitation specified in Rule 4460(i).

                      (b) FRACTIONAL SHARES. No fractional shares of Common
Stock shall be issued upon conversion of Series A Preferred and the number of
shares of Common Stock to be issued shall be rounded down to the nearest whole
share. The Company shall, in lieu of issuing any fractional share, pay the
holder otherwise entitled to such fraction a sum in cash equal to the fair
market value of such fraction on the date of conversion (as determined in good
faith by the Board of Directors).


                      (c) RESERVATION OF STOCK ISSUABLE UPON CONVERSION. The
Company shall at all times reserve and keep available out of its authorized but
unissued shares of Common Stock or its treasury shares, solely for the purpose
of effecting the conversion of the shares of the Series A Preferred, such number
of its shares of Common Stock as shall from time to time be sufficient to effect
the conversion of all outstanding shares of the Series A Preferred. If at any
time the number of authorized but unissued shares of Common Stock shall not be
sufficient to effect the conversion of all then outstanding shares of the Series
A Preferred, the Company will take such corporate action as may, in the opinion
of its counsel, be necessary to increase its authorized but unissued shares of
Common Stock to such number of shares as shall be sufficient for such purpose.


                                       5.


<PAGE>   11
                      (d) NOTICES. Any notice required by the provisions of this
Section 5 to be given to the holders of shares of the Series A Preferred shall
be deemed given upon the earlier of actual receipt or seventy-two (72) hours
after the same has been deposited in the United States mail, by certified or
registered mail, return receipt requested, and addressed to each holder of
record at the address of such holder appearing on the books of the Company.

                      (e) PAYMENT OF TAXES. The Company will pay all taxes
(other than taxes based upon income) and other governmental charges that may be
imposed with respect to the issue or delivery of shares of Common Stock upon
conversion of shares of Series A Preferred, excluding any tax or other charge
imposed in connection with any transfer involved in the issue and delivery of
shares of Common Stock in a name other than that in which the shares of Series A
Preferred so converted were registered.

               SECTION 6. NOTICES OF RECORD. Upon any taking by the Company of a
record of the holders of any class of securities for the purpose of determining
the holders thereof who are entitled to receive any dividend or other
distribution, or upon any capital reorganization of the Company, any
reclassification or recapitalization of the capital stock of the Company, any
merger or consolidation of the Company with or into any other corporation, or
any transfer of all or substantially all the assets of the Company to any other
person, or any voluntary or involuntary dissolution, liquidation or winding up
of the Company, or any shareholders' meeting to approve the terms thereof, the
Company shall mail to each holder of Series A Preferred at least twenty (20)
days prior to the record date specified therein a notice specifying (i) the date
on which any such record is to be taken for the purpose of such dividend or
distribution and a description of such dividend or distribution, (ii) the date
on which any such reorganization, reclassification, transfer, consolidation,
merger, dissolution, liquidation or winding up is expected to become effective,
and the date of the shareholders meeting to approve the terms thereof, if
applicable, (iii) the date, if any, that is to be fixed as to when the holders
of record of Common Stock (or other securities) shall be entitled to exchange
their shares of Common Stock (or other securities) for securities or other
property deliverable upon such reorganization, reclassification, transfer,
consolidation, merger, dissolution, liquidation or winding up, and (iv) the
material terms thereof.

               SECTION 7. NO REISSUANCE OF PREFERRED STOCK. No share or shares
of Series A Preferred acquired by the Company by reason of redemption, purchase,
conversion or otherwise shall be reissued.

               SECTION 8. RESTRICTION ON TRANSFER. Neither the shares of Series
A Preferred nor any right to receive redemption payments, nor any Contractual
Rights, shall be assigned, transferred, hypothecated or otherwise alienated by
the holder thereof without the prior written consent of the Company, except (i)
in connection with, and to the transferee of, all or substantially all of the
business and assets of such holder, or (ii) to a direct or indirect wholly owned
subsidiary of Baxter International, Inc. Any such attempted action shall be null
and void. The foregoing restriction shall not apply to any Common Stock issued
on conversion of the Preferred Stock.

               SECTION 9. CANCELLATION OF PREFERRED STOCK. Upon the effectuation
or consummation of any Covered Transaction pursuant to which the holders of the
Series A Preferred receive the Contractual Rights, the Series A Preferred shall
be canceled.


                                       6.


<PAGE>   12
        3. The authorized number of shares of Preferred Stock of this Company is
five million (5,000,000), none of which has been issued.

IN WITNESS WHEREOF, this Company has caused this Certificate to be signed by its
duly authorized officer this 6th day of July, 1998.


                                      CERUS CORPORATION



                                      By:   /s/ Stephen T. Isaacs
                                        -------------------------------
                                        Stephen T. Isaacs
                                        President


                          CERTIFICATES OF DESIGNATION
                               SERIES A PREFERRED


<PAGE>   13



                           CERTIFICATE OF DESIGNATION
                           OF SERIES B PREFERRED STOCK
                              OF CERUS CORPORATION


        The undersigned, Robert E. Miller, hereby certifies that:

        1. He is the duly elected and acting Chief Financial Officer of CERUS
CORPORATION, a Delaware corporation (the "Company"). The date of filing of the
Amended and Restated Certificate of Incorporation (the "Certificate") was
February 7, 1997.

        2. The Board of Directors of the Company adopted the following recitals
and resolutions as required by Section 151 of the General Company Law of the
State of Delaware by unanimous written consent dated June 30, 1998:

                WHEREAS, the Certificate provides for a class of shares known as
        Preferred Stock, issuable from time to time in one or more series; and

                WHEREAS, the Board of Directors of the Company is authorized by
        Section A of Article IV of the Certificate and, pursuant to its
        authority as aforesaid, desires to fix the terms of the second series of
        said Preferred Stock, the number of shares constituting said series and
        the designation of said series.

                NOW, THEREFORE, BE IT RESOLVED, that the Board of Directors
        deems it advisable to adopt, and hereby adopts, the following
        Certificate of Designation of Preferences of Series B Preferred Stock of
        the Company:

               SECTION 1. DESIGNATION. Three thousand three hundred twenty-seven
(3,327) shares of Preferred Stock, $0.001 par value, are designated "Series B
Preferred Stock" with the powers, preferences, rights, qualifications,
limitations and restrictions specified herein (the "Series B Preferred").

               SECTION 2. VOTING RIGHTS. The holders of shares of Series B
Preferred shall not have any voting rights, except as provided in Section 2,
Section 3(c)(1)(C), Section 3(c)(2) hereof, and as required under the General
Corporation Law of Delaware. Without first obtaining the affirmative vote or
written consent of the holders of at least a majority of the outstanding shares
of Series B Preferred Stock, voting together as a separate class, the Company
shall not authorize or issue shares of any class or series of stock, or
reclassify any class or series of stock, including without limitation, the
Company's Common Stock, into shares having preference or priority over the
Series B Preferred as to voting, liquidation preference or conversion rights.

               SECTION 3. LIQUIDATION RIGHTS.

                      (a) Upon any liquidation, dissolution, or winding up of
the Company, whether voluntary or involuntary, before any payment or
distribution of assets of the Company (whether capital or surplus) shall be made
to or set aside for the holders of Common Stock, Series A Preferred Stock, or
any other class or series of stock ranking junior to the Series B Preferred with
respect to liquidation preference, the holders of Series B Preferred shall be



<PAGE>   14
entitled to be paid out of the assets of the Company an amount per share of
Series B Preferred equal to the "Original Issue Price." The Original Issue Price
of the Series B Preferred shall be Two Thousand Eight Hundred Fifty-Four Dollars
Seventy-Nine and Three Tenths Cents ($2,854.793). If, upon any liquidation,
distribution, or winding up, the assets of the Company shall be insufficient to
make payment in full under this Section 3(a) to all holders of Series B
Preferred, then such assets shall be distributed among the holders of Series B
Preferred at the time outstanding, ratably in proportion to the full stated
amounts to which they would otherwise be respectively entitled under this
Section 3(a).

                      (b) The following events shall be considered a
liquidation, dissolution or winding up under this Section 3:

                           (1) any consolidation or merger of the Company with
or into any other corporation or other entity or person in which the Company is
not the surviving entity, or any other consolidation, merger, corporate
reorganization or other transaction or series of transactions pursuant to which
the holders of the outstanding voting securities of the Company immediately
prior to such consolidation, merger, reorganization or other transaction or
series of transactions fail to hold equity securities representing a majority of
the voting power of the surviving entity immediately following such
consolidation, merger or reorganization or any transaction or series of related
transactions; or

                           (2) a sale, lease or other disposition of all or
substantially all of the assets of the Company.

                      (c) Any securities to be delivered to the holders of the
Series B Preferred pursuant to a transaction treated as a liquidation shall be
valued as follows:

                           (1) Securities not subject to investment letter or
other similar restrictions on free marketability:

                                (A) If traded on a national securities exchange
or the National Market System of the National Association of Securities Dealers,
Inc. (the "NMS"), the value shall be deemed to be the average of the security's
closing prices on such exchange or the NMS over the thirty (30) day period
ending three (3) days prior to the closing;

                                (B) If traded over-the-counter (but not on the
NMS), the value shall be deemed to be the average of the mean of the closing bid
and ask prices over the thirty (30) day period ending three (3) days prior to
the closing; or

                                (C) If there is no active public market, the
value shall be the fair market value thereof, as mutually determined by the
Board of Directors of the Company and the holders of a majority of the
outstanding Series B Preferred, voting together as a single class.

                           (2) The method of valuation of securities subject to
investment letter or other restrictions on free marketability shall be to make
an appropriate discount from the market value determined as above in Sections
3(c)(1)(A), (B) or (C) to reflect the approximate fair market value thereof, as
mutually determined by the Board of Directors of the Company and


                                       2.


<PAGE>   15
the holders of not less than a majority of the outstanding Series B Preferred,
voting together as a single class.

               SECTION 4. REDEMPTION.

                      (a) The Company may elect to redeem all, but not less than
all, of the outstanding Series B Preferred at the Original Issue Price at any
time, from funds legally available for redemption. Without limiting the
foregoing, the Company shall have the right to redeem the outstanding Series B
Preferred within thirty (30) days after receipt of a Conversion Notice (as
defined below). Any redemption pursuant to this Section 4(b) shall be for all
shares of Series B Preferred then outstanding. In the event the Company desires
to redeem the Series B Preferred pursuant to this subsection (b), the Company
shall send a notice to the Series B Preferred holder stating that the Series B
Preferred shall be redeemed pursuant to this subsection (b); provided that, if
such notice is in response to a Conversion Notice, the notice must be sent
within thirty (30) days of receipt of the Conversion Notice. The amount to be
paid for the Series B Preferred being redeemed shall be referred to as the
"Redemption Price."

                      (b) Within five (5) days after receipt of a redemption
notice from the Company pursuant to Section 4(a) above, the Series B Preferred
holders shall surrender all Series B Preferred share certificates at the
principal executive office of the Company, and thereupon the Redemption Price
shall be payable, in cash to the order of the person whose name appears on such
certificate or certificates as the owner thereof and each surrendered
certificate shall be canceled. If the Company does not have sufficient funds
legally available to redeem all shares to be redeemed pursuant to this Section
4, then it shall use those funds which are legally available to redeem the
maximum possible number of such shares pro rata among the holders of the Series
B Preferred Stock. At any time thereafter when funds of the Company are legally
available for the redemption of shares of Series B Preferred, such funds will
immediately be used to redeem the balance of the shares which the Company has
become obligated to redeem pursuant to this Section 4 but which it has not
redeemed.

               SECTION 5. CONVERSION RIGHTS. The following provisions shall
apply with respect to the conversion of the Series B Preferred into shares of
Common Stock:

                      (a) OPTIONAL CONVERSION.

                           (1) At any time after the one-year anniversary of the
date of issuance of the Series B Preferred, each share of Series B Preferred
may, at the option of the holder, be converted at any time into that number of
fully paid and nonassessable shares of Common Stock equal to the Original Issue
Price divided by the Conversion Price (as defined below), subject to the
Company's right to redeem the Series B Preferred pursuant to Section 4(a) above.
The conversion price for the Series B Preferred shall initially be equal to the
Original Issue Price divided by 100 (the "Conversion Price"). Such initial
Conversion Price shall be adjusted from time to time in accordance with this
Section 5. All references to the Conversion Price herein shall mean the
Conversion Price as so adjusted.

                           (2) Notwithstanding anything contained in this
Section 5 to the contrary, the Series B Preferred shall not convert, and no
shares of Common Stock shall be issued by the Company thereby, unless and until
the pre-merger notification requirements of the Hart-Scott-Rodino Antitrust
Improvements Act of 1976, as amended (the "HSR Act"), have been


                                       3.


<PAGE>   16
complied with, and any waiting period under the HSR Act applicable to the
conversion of the Series B Preferred has expired or been terminated and any
approvals required thereunder have been obtained.

                           (3) Before any holder of Series B Preferred shall be
entitled to convert the same into shares of Common Stock, such holder shall
surrender the certificate or certificates therefor, duly endorsed, at the
principal executive office of the Company or its transfer agent for such stock,
and shall give written notice to the corporation at such office that such holder
elects to convert the Series B Preferred and shall state therein the name or
names in which the holder wishes the certificate or certificates for shares of
Common Stock to be issued (the "Conversion Notice"). The Company shall, as soon
as practicable thereafter, issue and deliver at such office to such holder of
Series B Preferred at the holder's address as set forth on the Company's
records, or such other address as the holder shall have furnished to the Company
in writing, a certificate or certificates for the number of shares of Common
Stock to which such holder shall be entitled as aforesaid. Such conversion shall
be deemed to have been made immediately prior to the close of business on the
date of surrender of the shares of Series B Preferred to be converted, and the
person or persons entitled to receive the shares of Common Stock issuable upon
such conversion shall be treated for all purposes as the record holder or
holders of such shares of Common Stock on such date.


                           (4) Notwithstanding anything contained in this
Section 5 to the contrary, in the event that the approval of the Company's
stockholders is required pursuant to Rule 4460(i) of the Nasdaq Stock Market
prior to the issuance of any of the shares of Common Stock issuable upon
conversion of the Series B Preferred, the Company shall obtain such approval by
the conversion date under Section 5(a)(1) hereof. In the event such approval is
not obtained, the Company shall, in accordance with Section 4 hereof, redeem any
shares of Series B Preferred that would be convertible into shares of Common
Stock in excess of the limitation specified in Rule 4460(i).


                      (b) ADJUSTMENT FOR STOCK SPLITS AND COMBINATIONS. If the
Company shall at any time or from time to time after the date that the first
share of Series B Preferred is issued (the "Original Issue Date") fix a record
date for the effectuation of a split or subdivision of the outstanding Common
Stock, the Conversion Price for the Series B Preferred in effect immediately
before that subdivision shall be proportionately decreased. Conversely, if the
Company shall at any time or from time to time after the Original Issue Date
combine the outstanding shares of Common Stock into a smaller number of shares,
the Conversion Price for the Series B Preferred in effect immediately before the
combination shall be proportionately increased. Any adjustment under this
Section 5(b) shall become effective at the close of business on the date the
split, subdivision or combination becomes effective.

                      (c) ADJUSTMENT FOR COMMON STOCK DIVIDENDS AND
DISTRIBUTIONS. If the Company at any time or from time to time after the
Original Issue Date makes, or fixes a record date for the determination of
holders of Common Stock entitled to receive, a dividend or other distribution
payable in additional shares of Common Stock, in each such event the Conversion
Price for the Series B Preferred that is then in effect shall be decreased as of
the time of such issuance or, in the event such record date is fixed, as of the
close of business on such


                                       4.


<PAGE>   17
record date, by multiplying the Conversion Price then in effect by a fraction
(i) the numerator of which is the total number of shares of Common Stock issued
and outstanding immediately prior to the time of such issuance or the close of
business on such record date, and (ii) the denominator of which is the total
number of shares of Common Stock issued and outstanding immediately prior to the
time of such issuance or the close of business on such record date plus the
number of shares of Common Stock issuable in payment of such dividend or
distribution; provided, however, that if such record date is fixed and such
dividend is not fully paid or if such distribution is not fully made on the date
fixed therefor, the Conversion Price shall be recomputed accordingly as of the
close of business on such record date and thereafter the Conversion Price shall
be adjusted pursuant to this Section 5(c) to reflect the actual payment of such
dividend or distribution or other securities or rights convertible into, or
entitling the holder thereof to receive directly or indirectly, additional
shares of Common Stock.

                      (d) ADJUSTMENTS FOR OTHER DIVIDENDS AND DISTRIBUTIONS. If
the Company at any time or from time to time after the Original Issue Date makes
or fixes a record date for the determination of holders of Common Stock entitled
to receive a dividend or other distribution payable in securities of the Company
other than shares of Common Stock, in each such event for purposes of this
subsection 5(d), provision shall be made so that the holders of the Series B
Preferred shall receive upon conversion thereof, in addition to the number of
shares of Common Stock receivable thereupon, the amount of other securities of
the Company which they would have received had their Series B Preferred been
converted into Common Stock as of the record date fixed for the determination of
the holders of Common Stock of the Company entitled to receive such distribution
and had they thereafter, during the period from the date of such event to and
including the conversion date, retained such securities receivable by them as
aforesaid during such period, subject to all other adjustments called for during
such period under this Section 5 with respect to the rights of the holders of
the Series B Preferred or with respect to such other securities by their terms.

                      (e) ADJUSTMENT FOR RECLASSIFICATION, EXCHANGE AND
SUBSTITUTION. If at any time or from time to time after the Original Issue Date,
the Common Stock issuable upon the conversion of the Series B Preferred is
changed into the same or a different number of shares of any class or classes of
stock, whether by recapitalization, reclassification or otherwise (other than a
subdivision or combination of shares or stock dividend or a reorganization,
merger, consolidation or sale of assets provided for elsewhere in this Section 5
or in Section 3), in any such event each holder of Series B Preferred shall have
the right thereafter to convert such stock into the kind and amount of stock and
other securities and property receivable upon such recapitalization,
reclassification or other change by holders of the maximum number of shares of
Common Stock into which such shares of Series B Preferred could have been
converted immediately prior to or as of such recapitalization, reclassification
or change, all subject to further adjustment as provided herein or with respect
to such other securities or property by the terms thereof. In any such case,
appropriate adjustment shall be made in the application of the provisions of
this Section 5 with respect to the rights of the holders of Series B Preferred
after such recapitalization, reclassification or change to the end that the
provisions of this Section 5 (including adjustment of the Conversion Price then
in effect and the number of shares issuable upon conversion of the Series B
Preferred) shall be applicable after that event and be as nearly equivalent as
practicable.


                                       5.


<PAGE>   18
                      (f) REORGANIZATIONS. If at any time or from time to time
after the Original Issue Date, there is a capital reorganization of the Common
Stock (other than a recapitalization, subdivision, combination,
reclassification, exchange or substitution of shares provided for elsewhere in
this Section 5 or in Section 3), as a part of such capital reorganization,
provision shall be made so that the holders of the Series B Preferred shall
thereafter be entitled to receive upon conversion of the Series B Preferred the
number of shares of stock or other securities or property of the Company or
otherwise to which a holder of the number of shares of Common Stock deliverable
upon conversion would have been entitled on such capital reorganization, subject
to adjustment in respect of such stock or securities by the terms thereof. In
any such case, appropriate adjustment shall be made in the application of the
provisions of this Section 5 with respect to the rights of the holders of Series
B Preferred after the capital reorganization to the end that the provisions of
this Section 5 (including adjustment of the Conversion Price then in effect and
the number of shares issuable upon conversion of the Series B Preferred) shall
be applicable after that event and be as nearly equivalent as practicable.

                      (g) FRACTIONAL SHARES. No fractional shares of Common
Stock shall be issued upon conversion of Series B Preferred and the number of
shares of Common Stock to be issued shall be rounded down to the nearest whole
share. The Company shall, in lieu of issuing any fractional share, pay the
holder otherwise entitled to such fraction a sum in cash equal to the fair
market value of such fraction on the date of conversion (as determined in good
faith by the Board of Directors).

                      (h) RESERVATION OF STOCK ISSUABLE UPON CONVERSION. The
Company shall at all times reserve and keep available out of its authorized but
unissued shares of Common Stock or its treasury shares, solely for the purpose
of effecting the conversion of the shares of the Series B Preferred, such number
of its shares of Common Stock as shall from time to time be sufficient to effect
the conversion of all outstanding shares of the Series B Preferred. If at any
time the number of authorized but unissued shares of Common Stock shall not be
sufficient to effect the conversion of all then outstanding shares of the Series
B Preferred, the Company will take such corporate action as may, in the opinion
of its counsel, be necessary to increase its authorized but unissued shares of
Common Stock to such number of shares as shall be sufficient for such purpose.

                      (i) NOTICES. Any notice required by the provisions of this
Section 5 to be given to the holders of shares of the Series B Preferred shall
be deemed given upon the earlier of actual receipt or seventy-two (72) hours
after the same has been deposited in the United States mail, by certified or
registered mail, return receipt requested, and addressed to each holder of
record at the address of such holder appearing on the books of the Company.

                      (j) PAYMENT OF TAXES. The Company will pay all taxes
(other than taxes based upon income) and other governmental charges that may be
imposed with respect to the issue or delivery of shares of Common Stock upon
conversion of shares of Series B Preferred, excluding any tax or other charge
imposed in connection with any transfer involved in the issue and delivery of
shares of Common Stock in a name other than that in which the shares of Series B
Preferred so converted were registered.

                      (k) NO DILUTION OR IMPAIRMENT. The Company shall not amend
its Certificate of Incorporation or participate in any reorganization, transfer
of assets, consolidation,


                                       6.


<PAGE>   19
merger, dissolution, issue or sale of securities or any other voluntary action,
for the purpose of avoiding or seeking to avoid the observance or performance of
any of the terms to be observed or performed hereunder by the Company, but shall
at all times in good faith assist in carrying out all such action as may be
reasonably necessary or appropriate in order to protect the conversion rights of
the holders of the Series B Preferred against dilution or other impairment.

               SECTION 6. NOTICES OF RECORD. Upon any taking by the Company of a
record of the holders of any class of securities for the purpose of determining
the holders thereof who are entitled to receive any dividend or other
distribution, or upon any capital reorganization of the Company, any
reclassification or recapitalization of the capital stock of the Company, any
merger or consolidation of the Company with or into any other corporation, or
any transfer of all or substantially all the assets of the Company to any other
person, or any voluntary or involuntary dissolution, liquidation or winding up
of the Company, or any shareholders' meeting to approve the terms thereof, the
Company shall mail to each holder of Series B Preferred at least twenty (20)
days prior to the record date specified therein a notice specifying (i) the date
on which any such record is to be taken for the purpose of such dividend or
distribution and a description of such dividend or distribution, (ii) the date
on which any such reorganization, reclassification, transfer, consolidation,
merger, dissolution, liquidation or winding up is expected to become effective,
and the date of the shareholders meeting to approve the terms thereof, if
applicable, (iii) the date, if any, that is to be fixed as to when the holders
of record of Common Stock (or other securities) shall be entitled to exchange
their shares of Common Stock (or other securities) for securities or other
property deliverable upon such reorganization, reclassification, transfer,
consolidation, merger, dissolution, liquidation or winding up, and (iv) the
material terms thereof.

               SECTION 7. NO REISSUANCE OF SERIES B PREFERRED STOCK. No share or
shares of Series B Preferred acquired by the Company by reason of redemption,
purchase, conversion or otherwise shall be reissued.

               SECTION 8. RESTRICTION ON TRANSFER. Neither the shares of Series
B Preferred nor any right to receive redemption payments shall be assigned,
transferred, hypothecated or otherwise alienated by the holder thereof without
the prior written consent of the Company, except (i) in connection with, and to
the transferee of, all or substantially all of the business and assets of such
holder, or (ii) to a direct or indirect wholly owned subsidiary of Baxter
International Inc. Any such attempted action shall be null and void. The
foregoing restriction shall not apply to any Common Stock issued on conversion
of the Series B Preferred.

The authorized number of shares of Preferred Stock of this Company is five
million (5,000,000), of which 5,000 shares designated as Series A Preferred
Stock are issued and outstanding.


                                       7.


<PAGE>   20
        IN WITNESS WHEREOF, this Company has caused this Certificate to be
signed by its duly authorized officer this 2nd day of March, 1999.

                                       CERUS CORPORATION



                                       By:   /s/ Robert E. Miller
                                          -------------------------------
                                          Robert E. Miller
                                          Chief Financial Officer



                           CERTIFICATE OF DESIGNATION
                               SERIES B PREFERRED
<PAGE>   21
                           CERTIFICATE OF DESIGNATION

                                       OF

                  SERIES C JUNIOR PARTICIPATING PREFERRED STOCK

                         (PURSUANT TO SECTION 151 OF THE
                        DELAWARE GENERAL CORPORATION LAW)

        CERUS CORPORATION, a corporation organized and existing under the
General Corporation Law of the State of Delaware (hereinafter called the
"Company"), hereby certifies that the following resolution was adopted by the
Board of Directors of the Corporation as required by Section 151 of the General
Corporation Law at a meeting duly called and held on November 3, 1999:

               RESOLVED, that pursuant to the authority granted to and vested in
        the Board of Directors of the Company in accordance with the provisions
        of its Amended and Restated Certificate of Incorporation, the Board of
        Directors hereby creates a series of Preferred Stock, par value $.001
        per share, of the Company and hereby states the designation and number
        of shares, and fixes the relative designations and the powers,
        preferences and rights, and the qualifications, limitations and
        restrictions thereof (in addition to the provisions set forth in the
        Certificate of Incorporation of the Company, which are applicable to the
        Preferred Stock of all classes and series), as follows:

Series C Junior Participating Preferred Stock:

        SECTION 1. DESIGNATION AND AMOUNT. Two hundred fifty thousand (250,000)
shares of Preferred Stock, $.001 par value, are designated "Series C Junior
Participating Preferred Stock" with the designations and the powers, preferences
and rights, and the qualifications, limitations and restrictions specified
herein (the "Junior Preferred Stock"). Such number of shares may be increased or
decreased by resolution of the Board of Directors; provided, that no decrease
shall reduce the number of shares of Junior Preferred Stock to a number less
than the number of shares then outstanding plus the number of shares reserved
for issuance upon the exercise of outstanding options, rights or warrants or
upon the conversion of any outstanding securities issued by the Company
convertible into Junior Preferred Stock.

                                       1.
<PAGE>   22

        SECTION 2. DIVIDENDS AND DISTRIBUTIONS.

                (A) Subject to the rights of the holders of any shares of any
series of Preferred Stock (or any similar stock) ranking prior and superior to
the Junior Preferred Stock with respect to dividends, the holders of shares of
Junior Preferred Stock, in preference to the holders of Common Stock, par value
$.001 per share (the "Common Stock"), of the Company, and of any other junior
stock, shall be entitled to receive, when, as and if declared by the Board of
Directors out of funds legally available for the purpose, quarterly dividends
payable in cash on the first day of April, July, October and January in each
year (each such date being referred to herein as a "Quarterly Dividend Payment
Date"), commencing on the first Quarterly Dividend Payment Date after the first
issuance of a share or fraction of a share of Junior Preferred Stock, in an
amount per share (rounded to the nearest cent) equal to the greater of (a) $l.00
or (b) subject to the provision for adjustment hereinafter set forth, 100 times
the aggregate per share amount of all cash dividends, and 100 times the
aggregate per share amount (payable in kind) of all non-cash dividends or other
distributions, other than a dividend payable in shares of Common Stock or a
subdivision of the outstanding shares of Common Stock (by reclassification or
otherwise), declared on the Common Stock since the immediately preceding
Quarterly Dividend Payment Date or, with respect to the first Quarterly Dividend
Payment Date, since the first issuance of any share or fraction of a share of
Junior Preferred Stock. In the event the Company shall at any time declare or
pay any dividend on the Common Stock payable in shares of Common Stock, or
effect a subdivision or combination or consolidation of the outstanding shares
of Common Stock (by reclassification or otherwise than by payment of a dividend
in shares of Common Stock) into a greater or lesser number of shares of Common
Stock, then in each such case the amount to which holders of shares of Junior
Preferred Stock were entitled immediately prior to such event under clause (b)
of the preceding sentence shall be adjusted by multiplying such amount by a
fraction, the numerator of which is the number of shares of Common Stock
outstanding immediately after such event and the denominator of which is the
number of shares of Common Stock that were outstanding immediately prior to such
event.

                (B) The Company shall declare a dividend or distribution on the
Junior Preferred Stock as provided in paragraph (A) of this Section immediately
after it declares a dividend or distribution on the Common Stock (other than a
dividend payable in shares of Common Stock); provided, that in the event no
dividend or distribution shall have been declared on the Common Stock during the
period between any Quarterly Dividend Payment Date and the next subsequent
Quarterly Dividend Payment Date, a dividend of $1.00 per share on the Junior
Preferred Stock shall nevertheless be payable on such subsequent Quarterly
Dividend Payment Date.

                (C) Dividends shall begin to accrue and be cumulative on
outstanding shares of Junior Preferred Stock from the Quarterly Dividend Payment
Date next preceding the date of issue of such shares, unless the date of issue
of such shares is prior to the record date for the first Quarterly Dividend
Payment Date, in which case dividends on such shares shall begin to accrue from
the date of issue of such shares, or unless the date of issue is a Quarterly
Dividend Payment Date or is a date after the record date for the determination
of holders of shares of Junior Preferred Stock entitled to receive a quarterly
dividend and before such Quarterly Dividend Payment Date, in either of which
events such dividends shall begin to accrue and be cumulative from such
Quarterly Dividend Payment Date. Accrued but unpaid dividends shall not bear


                                       2.
<PAGE>   23
interest. Dividends paid on the shares of Junior Preferred Stock in an amount
less than the total amount of such dividends at the time accrued and payable on
such shares shall be allocated pro rata on a share-by-share basis among all such
shares at the time outstanding. The Board of Directors may fix a record date for
the determination of holders of shares of Junior Preferred Stock entitled to
receive payment of a dividend or distribution declared thereon, which record
date shall be not more than 60 days prior to the date fixed for the payment
thereof.

        SECTION 3. VOTING RIGHTS. The holders of shares of Junior Preferred
Stock shall have the following voting rights:

                (A) Subject to the provision for adjustment hereinafter set
forth, each share of Junior Preferred Stock shall entitle the holder thereof to
100 votes on all matters submitted to a vote of the stockholders of the Company.
In the event the Company shall at any time declare or pay any dividend on the
Common Stock payable in shares of Common Stock, or effect a subdivision or
combination or consolidation of the outstanding shares of Common Stock (by
reclassification or otherwise than by payment of a dividend in shares of Common
Stock) into a greater or lesser number of shares of Common Stock, then in each
such case the number of votes per share to which holders of shares of Junior
Preferred Stock were entitled immediately prior to such event shall be adjusted
by multiplying such number by a fraction, the numerator of which is the number
of shares of Common Stock outstanding immediately after such event and the
denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event.

                (B) Except as otherwise provided herein, in any other
Certificate of Designation creating a series of Preferred Stock or any similar
stock, or by law, the holders of shares of Junior Preferred Stock and the
holders of shares of Common Stock and any other capital stock of the Company
having general voting rights shall vote together as one class on all matters
submitted to a vote of stockholders of the Company.

                (C) Except as set forth herein, or as otherwise provided by law,
holders of Junior Preferred Stock shall have no special voting rights and their
consent shall not be required (except to the extent they are entitled to vote
with holders of Common Stock as set forth herein) for taking any corporate
action.

        SECTION 4. CERTAIN RESTRICTIONS.

                (A) Whenever quarterly dividends or other dividends or
distributions payable on the Junior Preferred Stock as provided in Section 2 are
in arrears, thereafter and until all accrued and unpaid dividends and
distributions, whether or not declared, on shares of Junior Preferred Stock
outstanding shall have been paid in full, the Company shall not:

                        (i) declare or pay dividends, or make any other
distributions, on any shares of stock ranking junior (either as to dividends or
upon liquidation, dissolution or winding up) to the Junior Preferred Stock;

                        (ii) declare or pay dividends, or make any other
distributions, on any shares of stock ranking on a parity (either as to
dividends or upon liquidation, dissolution or winding up) with the Junior
Preferred Stock, except dividends paid ratably on the Junior


                                       3.
<PAGE>   24
Preferred Stock and all such parity stock on which dividends are payable or in
arrears in proportion to the total amounts to which the holders of all such
shares are then entitled;

                        (iii) redeem or purchase or otherwise acquire for
consideration shares of any stock ranking junior (either as to dividends or upon
liquidation, dissolution or winding up) to the Junior Preferred Stock, provided
that the Company may at any time redeem, purchase or otherwise acquire shares of
any such junior stock in exchange for shares of any stock of the Company ranking
junior (either as to dividends or upon dissolution, liquidation or winding up)
to the Junior Preferred Stock; or

                        (iv) redeem or purchase or otherwise acquire for
consideration any shares of Junior Preferred Stock, or any shares of stock
ranking on a parity (either as to dividends or upon liquidation, dissolution or
winding up) with the Junior Preferred Stock, except in accordance with a
purchase offer made in writing or by publication (as determined by the Board of
Directors) to all holders of such shares upon such terms as the Board of
Directors, after consideration of the respective annual dividend rates and other
relative rights and preferences of the respective series and classes, shall
determine in good faith will result in fair and equitable treatment among the
respective series or classes.

                (B) The Company shall not permit any subsidiary of the Company
to purchase or otherwise acquire for consideration any shares of stock of the
Company unless the Company could, under paragraph (A) of this Section 4,
purchase or otherwise acquire such shares at such time and in such manner.

        SECTION 5. REACQUIRED SHARES. Any shares of Junior Preferred Stock
purchased or otherwise acquired by the Company in any manner whatsoever shall be
retired and cancelled promptly after the acquisition thereof. All such shares
shall upon their cancellation become authorized but unissued shares of Preferred
Stock and may be reissued as part of a new series of Preferred Stock subject to
the conditions and restrictions on issuance set forth herein, in the Amended and
Restated Certificate of Incorporation, or in any other Certificate of
Designation creating a series of Preferred Stock or any similar stock or as
otherwise required by law.

        SECTION 6. LIQUIDATION, DISSOLUTION OR WINDING UP. Upon any liquidation,
dissolution or winding up of the Company, no distribution shall be made (1) to
the holders of shares of stock ranking junior (either as to dividends or upon
liquidation, dissolution or winding up) to the Junior Preferred Stock unless,
prior thereto, the holders of shares of Junior Preferred Stock shall have
received $100 per share, plus an amount equal to accrued and unpaid dividends
and distributions thereon, whether or not declared, to the date of such payment,
provided that the holders of shares of Junior Preferred Stock shall be entitled
to receive an aggregate amount per share, subject to the provision for
adjustment hereinafter set forth, equal to 100 times the aggregate amount to be
distributed per share to holders of shares of Common Stock, or (2) to the
holders of shares of stock ranking on a parity (either as to dividends or upon
liquidation, dissolution or winding up) with the Junior Preferred Stock, except
distributions made ratably on the Junior Preferred Stock and all such parity
stock in proportion to the total amounts to which the holders of all such shares
are entitled upon such liquidation, dissolution or winding up. In the event the
Company shall at any time declare or pay any dividend on the Common Stock
payable in shares of Common Stock, or effect a subdivision or combination or
consolidation of


                                       4.
<PAGE>   25

the outstanding shares of Common Stock (by reclassification or otherwise than by
payment of a dividend in shares of Common Stock) into a greater or lesser number
of shares of Common Stock, then in each such case the aggregate amount to which
holders of shares of Junior Preferred Stock were entitled immediately prior to
such event under the proviso in clause (1) of the preceding sentence shall be
adjusted by multiplying such amount by a fraction the numerator of which is the
number of shares of Common Stock outstanding immediately after such event and
the denominator of which is the number of shares of Common Stock that were
outstanding immediately prior to such event.

        SECTION 7. CONSOLIDATION, MERGER, ETC. In case the Company shall enter
into any consolidation, merger, combination or other transaction in which the
shares of Common Stock are exchanged for or changed into other stock or
securities, cash and/or any other property, then in any such case each share of
Junior Preferred Stock shall at the same time be similarly exchanged or changed
into an amount per share, subject to the provision for adjustment hereinafter
set forth, equal to 100 times the aggregate amount of stock, securities, cash
and/or any other property (payable in kind), as the case may be, into which or
for which each share of Common Stock is changed or exchanged. In the event the
Company shall at any time declare or pay any dividend on the Common Stock
payable in shares of Common Stock, or effect a subdivision or combination or
consolidation of the outstanding shares of Common Stock (by reclassification or
otherwise than by payment of a dividend in shares of Common Stock) into a
greater or lesser number of shares of Common Stock, then in each such case the
amount set forth in the preceding sentence with respect to the exchange or
change of shares of Junior Preferred Stock shall be adjusted by multiplying such
amount by a fraction, the numerator of which is the number of shares of Common
Stock outstanding immediately after such event and the denominator of which is
the number of shares of Common Stock that were outstanding immediately prior to
such event.

        SECTION 8. NO REDEMPTION. The shares of Junior Preferred Stock shall not
be redeemable.

        SECTION 9. RANK. The Junior Preferred Stock shall rank, with respect to
the payment of dividends and the distribution of assets, junior to all series of
any other class of the Company's Preferred Stock (including the Company's Series
A Preferred Stock notwithstanding any provisions of the Certificate of
Designation of Series A Preferred Stock of the Company to the contrary).

        SECTION 10. AMENDMENT. The Amended and Restated Certificate of
Incorporation of the Company shall not be amended in any manner which would
materially alter or change the powers, preferences or special rights of the
Junior Preferred Stock so as to affect them adversely without the affirmative
vote of the holders of at least two-thirds of the outstanding shares of Junior
Preferred Stock, voting together as a single class.


                                       5.
<PAGE>   26
        IN WITNESS WHEREOF, the undersigned have executed this certificate as of
November 3, 1999.
                                            /s/ STEPHEN T. ISAACS
                                            ------------------------------------
                                            STEPHEN T. ISAACS
                                            PRESIDENT AND CEO

                                            /s/ LORI ROLL
                                            ------------------------------------
                                            LORI ROLL
                                            SECRETARY


                                       6.

<PAGE>   1
                                                                    EXHIBIT 99.1

Contact:

    Cerus Corporation                     Noonan/Russo Communications, Inc.
    (925) 603-9071                        (415) 677-4455
    Stephen Isaacs, President and CEO     Amy Giller, Investors
    Greg W. Schafer, CFO                  Amy Flood, Media

                CERUS CORPORATION ADOPTS STOCKHOLDER RIGHTS PLAN

Concord, Calif., November 3, 1999 -- Cerus Corporation (Nasdaq: CERS) announced
that its Board of Directors approved the adoption of a Stockholder Rights Plan
under which all stockholders of record as of November 23, 1999 will receive
rights to purchase shares of a new series of Preferred Stock.

The Rights Plan is designed to enable all Cerus stockholders to realize the full
value of their investment and to provide for fair and equal treatment for all
stockholders in the event that an unsolicited attempt is made to acquire Cerus.
The adoption of the Rights Plan is intended as a means to guard against abusive
takeover tactics and is not in response to any particular proposal.

The rights will be distributed as a non-taxable dividend and will expire ten
years from the record date. The rights will be exercisable only if a person or
group acquires 15% or more of the Cerus Corporation Common Stock or announces a
tender offer for fifteen percent or more of the Common Stock. If a person or
group acquires 15% or more of the company's Common Stock, all rightsholders
except the buyer will be entitled to acquire the company's Common Stock at a
discount. Baxter Healthcare Corporation will be exempt from the Rights Plan,
unless Baxter acquires beneficial ownership of 20.1% or more of the Company's
Common Stock, excluding for this purpose shares of the company's Common Stock
issuable upon conversion of Preferred Stock of Cerus now held by Baxter. The
effect will be to discourage acquisitions of more than 15% of the Common Stock
of Cerus without negotiations with the Board.


<PAGE>   2
The rights will trade with the company's Common Stock, unless and until they are
separated upon the occurrence of certain future events. The company's Board of
Directors may terminate the Rights Plan at any time or redeem the rights prior
to the time a person acquires more than 15% of the company's Common Stock.
Additional details regarding the Rights Plan will be outlined in a summary to be
mailed to all stockholders following the record date.

Cerus Corporation is a leading developer of systems to improve the safety of
transfusion blood products through inactivation of viruses, bacteria and other
pathogens. In addition to systems to treat platelets, plasma and red blood cells
intended for transfusion, Cerus is developing a system to treat source plasma
used for fractionation into various plasma products. The company's platform
technologies, which prevent viral, bacterial and other cellular replication,
have potential applications in the health care field beyond pathogen
inactivation in blood components. Cerus has collaboration agreements with Baxter
Healthcare and the Consortium for Plasma Science.

Statements in this news release are forward-looking statements that involve
risks and uncertainties. Actual results could differ materially from the above
forward-looking statements as a result of certain factors, including factors
discussed in the company's 1998 Annual Report on Form 10-K.

                                       ###




<PAGE>   1
                                                                    EXHIBIT 99.2


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

                               CERUS CORPORATION

                                      AND

                         NORWEST BANK MINNESOTA, N.A.,
                                AS RIGHTS AGENT

                                RIGHTS AGREEMENT


                          DATED AS OF NOVEMBER 3, 1999

- --------------------------------------------------------------------------------
<PAGE>   2
                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                         PAGE
                                                                                         ----
<S>         <C>                                                                          <C>
SECTION 1.  CERTAIN DEFINITIONS........................................................   1

SECTION 2.  APPOINTMENT OF RIGHTS AGENT................................................   4

SECTION 3.  ISSUE OF RIGHT CERTIFICATES................................................   4

SECTION 4.  FORM OF RIGHT CERTIFICATES.................................................   6

SECTION 5.  COUNTERSIGNATURE AND REGISTRATION..........................................   6

SECTION 6.  TRANSFER, SPLIT UP, COMBINATION AND EXCHANGE OF RIGHT CERTIFICATES;
                MUTILATED, DESTROYED, LOST OR STOLEN RIGHT CERTIFICATES................   7

SECTION 7.  EXERCISE OF RIGHTS; PURCHASE PRICE; EXPIRATION DATE OF RIGHTS..............   8

SECTION 8.  CANCELLATION AND DESTRUCTION OF RIGHT CERTIFICATES.........................   9

SECTION 9.  AVAILABILITY OF PREFERRED SHARES...........................................   9

SECTION 10. PREFERRED SHARES RECORD DATE...............................................  10

SECTION 11. ADJUSTMENT OF PURCHASE PRICE, NUMBER OF SHARES OR NUMBER OF RIGHTS.........  11

SECTION 12. CERTIFICATE OF ADJUSTED PURCHASE PRICE OR NUMBER OF SHARES.................  17

SECTION 13. CONSOLIDATION, MERGER OR SALE OR TRANSFER OF ASSETS OR EARNING POWER.......  18

SECTION 14. FRACTIONAL RIGHTS AND FRACTIONAL SHARES....................................  20

SECTION 15. RIGHTS OF ACTION...........................................................  22

SECTION 16. AGREEMENT OF RIGHT HOLDERS.................................................  22

SECTION 17. RIGHT CERTIFICATE HOLDER NOT DEEMED A STOCKHOLDER..........................  22

SECTION 18. CONCERNING THE RIGHTS AGENT................................................  23

SECTION 19. MERGER OR CONSOLIDATION OR CHANGE OF NAME OF RIGHTS AGENT..................  23

SECTION 20. DUTIES OF RIGHTS AGENT.....................................................  24

SECTION 21. CHANGE OF RIGHTS AGENT.....................................................  26

SECTION 22. ISSUANCE OF NEW RIGHT CERTIFICATES.........................................  26

SECTION 23. REDEMPTION.................................................................  27

SECTION 24. EXCHANGE...................................................................  28

SECTION 25. NOTICE OF CERTAIN EVENTS...................................................  30

SECTION 26. NOTICES....................................................................  31

SECTION 27. SUPPLEMENTS AND AMENDMENTS.................................................  31

SECTION 28. DETERMINATION AND ACTIONS BY THE BOARD OF DIRECTORS, ETC...................  32
</TABLE>

                                       i.
<PAGE>   3
                                TABLE OF CONTENTS
                                   (CONTINUED)

<TABLE>
<CAPTION>
                                                                                        PAGE
                                                                                        ----
<S>         <C>                                                                         <C>
SECTION 29. SUCCESSORS.................................................................  32

SECTION 30. BENEFITS OF THIS AGREEMENT.................................................  32

SECTION 31. SEVERABILITY...............................................................  32

SECTION 32. GOVERNING LAW..............................................................  32

SECTION 33. COUNTERPARTS...............................................................  33

SECTION 34. DESCRIPTIVE HEADINGS.......................................................  33
</TABLE>


                                       ii
<PAGE>   4
                                RIGHTS AGREEMENT


      THIS RIGHTS AGREEMENT ("Agreement"), dated as of November 3, 1999, between
CERUS CORPORATION, a Delaware corporation (the "Company"), and NORWEST BANK
MINNESOTA, N.A. ("Rights Agent").

      The Board of Directors of the Company has authorized and declared a
dividend of one preferred share purchase right (a "Right") for each Common Share
(as such term is hereinafter defined) outstanding at the close of business on
November 23, 1999 (the "Record Date"), each Right representing the right to
purchase one one-hundredth of a Preferred Share (as such term is hereinafter
defined), upon the terms and subject to the conditions herein set forth, and has
further authorized and directed the issuance of one Right with respect to each
Common Share that shall become outstanding between the Record Date and the
earliest to occur of the Distribution Date, the Redemption Date and the Final
Expiration Date (as such terms are hereinafter defined); provided, however, that
Rights may be issued with respect to Common Shares that shall become outstanding
after the Distribution Date and prior to the earlier of the Redemption Date and
the Final Expiration Date in accordance with the provisions of Section 22
hereof.

      Accordingly, in consideration of the premises and the mutual agreements
herein set forth, the parties hereby agree as follows:

SECTION 1. CERTAIN DEFINITIONS. For purposes of this Agreement, the following
terms have the meanings indicated:

      (a) "ACQUIRING PERSON" shall mean any Person (as such term is hereinafter
defined) who or which, together with all Affiliates and Associates (as such
terms are hereinafter defined) of such Person, shall be the Beneficial Owner (as
such term is hereinafter defined) of 15% or more of the Common Shares then
outstanding. Notwithstanding the foregoing, (A) the term Acquiring Person shall
not include (i) the Company, (ii) any Subsidiary (as such term is hereinafter
defined) of the Company, (iii) any employee benefit or compensation plan of the
Company or any Subsidiary of the Company, (iv) any entity holding Common Shares
for or pursuant to the terms of any such employee benefit or compensation plan,
or (v) an Excluded Stockholder (as such term is hereinafter defined) and (B) no
Person shall become an "Acquiring Person" either (x) as the result of an
acquisition of Common Shares by the Company which, by reducing the number of
shares outstanding, increases the proportionate number of shares beneficially
owned by such Person to 15% or more (or in the case of Baxter (as defined
below), more than the Permissible Baxter Amount (as defined below)) of the
Common Shares then outstanding; provided, however, that if a Person shall become
the Beneficial Owner of 15% or more (or in the case of Baxter, more than the
Permissible Baxter Amount) of the Common Shares then outstanding by reason of
share purchases by the Company and shall, following written notice from, or
public disclosure by the Company of such share purchases by the Company, become
the Beneficial Owner of any additional Common Shares without the prior consent
of the Company and shall then Beneficially Own more than 15% (or in the case of
Baxter, more than the Permissible Baxter Amount) of the Common Shares then
outstanding, then such Person shall be deemed to be an "Acquiring Person," or
(y) if the Board of Directors determines in good faith that a Person who would
otherwise be an "Acquiring Person," as


                                       1.
<PAGE>   5
defined pursuant to the foregoing provisions of this paragraph (a), has become
such inadvertently, and such Person divests, as promptly as practicable (as
determined in good faith by the Board of Directors), but in any event within
five Business Days, following receipt of written notice from the Company of such
event, of Beneficial Ownership of a sufficient number of Common Shares so that
such Person would no longer be an Acquiring Person, as defined pursuant to the
foregoing provisions of this paragraph (a), then such Person shall not be deemed
to be an "Acquiring Person" for any purposes of this Agreement; provided,
however, that if such Person shall again become the Beneficial Owner of 15% or
more (or in the case of Baxter, more than the Permissible Baxter Amount) of the
Common Shares then outstanding, such Person shall be deemed an "Acquiring
Person," subject to the exceptions set forth in this Section 1(a).

      (b) "AFFILIATE" and "ASSOCIATE" shall have the respective meanings
ascribed to such terms in Rule 12b-2 of the General Rules and Regulations under
the Securities Exchange Act of 1934, as amended (the "Exchange Act"), as in
effect on the date of this Agreement.

      (c) A Person shall be deemed the "BENEFICIAL OWNER" of and shall be deemed
to "beneficially own" any securities:

            (i) which such Person or any of such Person's Affiliates or
Associates is deemed to beneficially own, within the meaning of Rule 13d-3 of
the General Rules and Regulations under the Exchange Act as in effect on the
date of this Rights Agreement;

            (ii) which such Person or any of such Person's Affiliates or
Associates has (A) the right to acquire (whether such right is exercisable
immediately or only after the passage of time) pursuant to any agreement,
arrangement or understanding (other than customary agreements with and between
underwriters and selling group members with respect to a bona fide public
offering of securities, or upon the exercise of conversion rights, exchange
rights, rights (other than these Rights), warrants or options, or otherwise;
provided, however, that a Person shall not be deemed the Beneficial Owner of, or
to beneficially own, securities tendered pursuant to a tender or exchange offer
made by or on behalf of such Person or any of such Person's Affiliates or
Associates until such tendered securities are accepted for purchase or exchange;
or (B) the right to vote pursuant to any agreement, arrangement or
understanding; provided, however, that a Person shall not be deemed the
Beneficial Owner of, or to beneficially own, any security if the agreement,
arrangement or understanding to vote such security (1) arises solely from a
revocable proxy or consent given to such Person in response to a public proxy or
consent solicitation made pursuant to, and in accordance with, the applicable
rules and regulations promulgated under the Exchange Act and (2) is not also
then reportable on Schedule 13D under the Exchange Act (or any comparable or
successor report); or

            (iii) which are beneficially owned, directly or indirectly, by any
other Person with which such Person or any of such Person's Affiliates or
Associates has any agreement, arrangement or understanding (other than customary
agreements with and between underwriters and selling group members with respect
to a bona fide public offering of securities) for the purpose of acquiring,
holding, voting (except to the extent contemplated by the proviso to Section
1(c)(ii)(B) hereof) or disposing of any securities of the Company.


                                       2.
<PAGE>   6
      Notwithstanding anything in this definition of Beneficial Ownership to the
contrary, the phrase, "then outstanding," when used with reference to a Person's
Beneficial Ownership of securities of the Company, shall mean the number of such
securities then issued and outstanding together with the number of such
securities not then actually issued and outstanding which such Person would be
deemed to own beneficially hereunder.

      (d) "BUSINESS DAY" shall mean any day other than a Saturday, a Sunday, or
a day on which banking institutions in the State of Minnesota are authorized or
obligated by law or executive order to close.

      (e) "CLOSE OF BUSINESS" on any given date shall mean 5:00 p.m., Pacific
Time, on such date; provided, however, that if such date is not a Business Day
it shall mean 5:00 p.m., Pacific Time, on the next succeeding Business Day.

      (f) "COMMON SHARES" shall mean the shares of common stock, par value $.001
per share, of the Company; provided, however, that, "Common Shares," when used
in this Agreement in connection with a specific reference to any Person other
than the Company, shall mean the capital stock (or equity interest) with the
greatest voting power of such other Person or, if such other Person is a
Subsidiary of another Person, the Person or Persons which ultimately control
such first-mentioned Person.

      (g) "DISTRIBUTION DATE" shall have the meaning set forth in Section 3
hereof.

      (h) "EXCLUDED STOCKHOLDER" shall mean Baxter Healthcare Corporation, a
Delaware corporation ("Baxter") (including its Affiliates and Associates);
provided, however, that Baxter (including its Affiliates and Associates) shall
not be an Excluded Stockholder if Baxter (including its Affiliates and
Associates) becomes without the prior approval of the Board of Directors of the
Company the Beneficial Owner of more than the Permissible Baxter Amount. For
purposes of this Agreement, the "Permissible Baxter Amount" shall mean an amount
equal to 20.1% of the Common Shares then outstanding excluding for this purpose
any and all Common Shares deemed to be owned through Baxter's ownership of
Series A Preferred Stock of the Company as a result of the transactions
contemplated by that certain Series A Preferred Stock Purchase Agreement dated
June 30, 1998 and Series B Preferred Stock of the Company as a result of the
transactions contemplated by that certain Series B Preferred Stock Purchase
Agreement between Baxter and the Company dated June 30, 1998.

      (i) "FINAL EXPIRATION DATE" shall have the meaning set forth in Section 7
hereof.

      (j) "INTERESTED STOCKHOLDER" shall mean any Acquiring Person or any
Affiliate or Associate of an Acquiring Person or any other Person in which any
such Acquiring Person, Affiliate or Associate has an interest, or any other
Person acting directly or indirectly on behalf of or in concert with any such
Acquiring Person, Affiliate or Associate.

      (k) "PERSON" shall mean any individual, firm, corporation or other entity,
and shall include any successor (by merger or otherwise) of such entity.

      (l) "PREFERRED SHARES" shall mean shares of Series C Junior Participating
Preferred Stock, par value $.001 per share, of the Company having the
designations and the powers,


                                       3.
<PAGE>   7
preferences and rights, and the qualifications, limitations and restrictions set
forth in the Form of Certificate of Designation attached to this Agreement as
Exhibit A.

      (m) "PURCHASE PRICE" shall have the meaning set forth in Section 7(b)
hereof.

      (n) "REDEMPTION DATE" shall have the meaning set forth in Section 7
hereof.

      (o) "SHARES ACQUISITION DATE" shall mean the first date of public
announcement by the Company or an Acquiring Person that an Acquiring Person has
become such provided, however that, if such Person is determined not to have
become an Acquiring Person pursuant to clause (y) of Subsection 1(a)(B) hereof,
then no Shares Acquisition Date shall be deemed to have occurred.

      (p) "SUBSIDIARY" of any Person shall mean any corporation or other entity
of which a majority of the voting power of the voting equity securities or
equity interest is owned, directly or indirectly, by such Person.

      (q) "TRANSACTION" shall mean any merger, consolidation or sale of assets
described in Section 13(a) hereof or any acquisition of Common Shares which
would result in a Person becoming an Acquiring Person or a Principal Party (as
such term is hereinafter defined).

      (r) "TRANSACTION PERSON" with respect to a Transaction shall mean (i) any
Person who (x) is or will become an Acquiring Person or a Principal Party (as
such term is hereinafter defined) if the Transaction were to be consummated and
(y) directly or indirectly proposed or nominated a director of the Company which
director is in office at the time of consideration of the Transaction, or (ii)
an Affiliate or Associate of such a Person.

SECTION 2. APPOINTMENT OF RIGHTS AGENT. The Company hereby appoints the Rights
Agent to act as agent for the Company in accordance with the terms and
conditions hereof, and the Rights Agent hereby accepts such appointment. The
Company may from time to time appoint such co-Rights Agents as it may deem
necessary or desirable.

SECTION 3. ISSUE OF RIGHT CERTIFICATES.

      (a) Until the earlier of (i) the Shares Acquisition Date or (ii) the tenth
Business Day (or such later date as may be determined by action of the Board of
Directors prior to such time as any Person becomes an Acquiring Person) after
the date of the commencement (determined in accordance with Rule 14d-2 under the
Exchange Act) by any Person (other than the Company, any Subsidiary of the
Company, any employee benefit plan of the Company or of any Subsidiary of the
Company or any entity holding Common Shares for or pursuant to the terms of any
such plan) of, or of the first public announcement of the intention of any
Person (other than the Company, any Subsidiary of the Company, any employee
benefit plan of the Company or of any Subsidiary of the Company or any entity
holding Common Shares for or pursuant to the terms of any such plan) to
commence, a tender or exchange offer (which intention to commence remains in
effect for five Business Days after such announcement), the consummation of
which would result in any Person becoming an Acquiring Person (including any
such date which is after the date of this Agreement and prior to the issuance of
the Rights, the earlier of such dates being herein referred to as the
"Distribution Date"), (x) the Rights will be evidenced by the certificates


                                       4.
<PAGE>   8
for Common Shares registered in the names of the holders thereof (which
certificates shall also be deemed to be Right Certificates) and not by separate
Right Certificates, and (y) the Rights (and the right to receive Right
Certificates therefor) will be transferable only in connection with the transfer
of Common Shares. As soon as practicable after the Distribution Date, the
Company will prepare and execute, the Rights Agent will countersign, and the
Company will send or cause to be sent (and the Rights Agent will, if requested,
send) by first-class, insured, postage-prepaid mail, to each record holder of
Common Shares as of the Close of Business on the Distribution Date, at the
address of such holder shown on the records of the Company, a Right Certificate,
in substantially the form of Exhibit B hereto (a "Right Certificate"),
evidencing one Right for each Common Share so held, subject to the adjustment
provisions of Section 11 of this Rights Agreement. As of the Distribution Date,
the Rights will be evidenced solely by such Right Certificates.

      (b) On the Record Date, or as soon as practicable thereafter, the Company
will send (directly or through the Rights Agent or its transfer agent) a copy of
a Summary of Rights to Purchase Preferred Shares, in substantially the form of
Exhibit C hereto (the "Summary of Rights"), by first-class, postage-prepaid
mail, to each record holder of Common Shares as of the Close of Business on the
Record Date, at the address of such holder shown on the records of the Company.
With respect to certificates for Common Shares outstanding as of the Record
Date, until the Distribution Date, the Rights will be evidenced by such
certificates registered in the names of the holders thereof. Until the
Distribution Date (or the earlier of the Redemption Date and the Final
Expiration Date), the surrender for transfer of any certificate for Common
Shares outstanding on the Record Date shall also constitute the transfer of the
Rights associated with the Common Shares represented thereby.

      (c) Certificates for Common Shares which become outstanding (including,
without limitation, reacquired Common Shares referred to in the last sentence of
this paragraph (c)) after the Record Date but prior to the earliest of the
Distribution Date, the Redemption Date or the Final Expiration Date shall have
impressed on, printed on, written on or otherwise affixed to them the following
legend:

            This certificate also evidences and entitles the holder hereof to
      certain rights as set forth in a Rights Agreement between Cerus
      Corporation (the "Company") and Norwest Bank Minnesota, N.A. as Rights
      Agent (the "Rights Agent"), dated as of November 3, 1999, as amended from
      time to time (the "Rights Agreement"), the terms of which are hereby
      incorporated herein by reference and a copy of which is on file at the
      principal executive offices of the Company. Under certain circumstances,
      as set forth in the Rights Agreement, such Rights will be evidenced by
      separate certificates and will no longer be evidenced by this certificate.
      The Company will mail to the holder of this certificate a copy of the
      Rights Agreement without charge after receipt of a written request
      therefor. As described in the Rights Agreement, Rights issued to any
      Person who becomes an Acquiring Person or an Affiliate or Associate
      thereof (as defined in the Rights Agreement) and certain related persons,
      whether currently held by or on behalf of such Person or by any subsequent
      holder, shall become null and void.


                                       5.
<PAGE>   9
      With respect to such certificates containing the foregoing legend, until
the Distribution Date, the Rights associated with the Common Shares represented
by such certificates shall be evidenced by such certificates alone, and the
surrender for transfer of any such certificate shall also constitute the
transfer of the Rights associated with the Common Shares represented thereby. In
the event that the Company purchases or acquires any Common Shares after the
Record Date but prior to the Distribution Date, any Rights associated with such
Common Shares shall be deemed canceled and retired so that the Company shall not
be entitled to exercise any Rights associated with the Common Shares which are
no longer outstanding. Notwithstanding this Section 3(c), the omission of a
legend shall not affect the enforceability of any part of this Rights Agreement
or the rights of any holder of the Rights.

SECTION 4. FORM OF RIGHT CERTIFICATES.

      (a) The Right Certificates (and the form of election to purchase Preferred
Shares, the form of assignment and the form of certification to be printed on
the reverse thereof) shall be substantially the same as Exhibit B hereto and may
have such marks of identification or designation and such legends, summaries or
endorsements printed thereon as the Company may deem appropriate and as are not
inconsistent with the provisions of this Agreement, or as may be required to
comply with any applicable law or with any rule or regulation made pursuant
thereto or with any rule or regulation of any stock exchange or quotation system
on which the Rights may from time to time be listed, or to conform to usage.
Subject to the provisions of Sections 7, 11 and 22 hereof, the Right
Certificates shall entitle the holders thereof to purchase such number of one
one-hundredths of a Preferred Share as shall be set forth therein at the price
per one one-hundredth of a Preferred Share set forth therein (the "Purchase
Price"), but the number of such one one-hundredths of a Preferred Share and the
Purchase Price shall be subject to adjustment as provided herein.

      (b) Any Right Certificate issued pursuant to Section 3(a) or Section 22
hereof that represents Rights which are null and void pursuant to Section
11(a)(ii) hereof and any Right Certificate issued pursuant to Section 6 or
Section 11 hereof upon transfer, exchange, replacement or adjustment of any
other Right Certificate referred to in this sentence, shall contain (to the
extent feasible) the following legend:

      The Rights represented by this Right Certificate are or were beneficially
owned by a Person who was or became an Acquiring Person or an Affiliate or
Associate of an Acquiring Person (as such terms are defined in the Rights
Agreement). Accordingly, this Right Certificate and the Rights represented
hereby are null and void.

      The provisions of Section 11(a)(ii) hereof shall be operative whether or
not the foregoing legend is contained on any such Right Certificate.

SECTION 5. COUNTERSIGNATURE AND REGISTRATION. The Right Certificates shall be
executed on behalf of the Company by its Chairman of the Board, its Chief
Executive Officer, its President, its Vice Chairman of the Board, its Chief
Financial Officer, or any of its Vice Presidents, either manually or by
facsimile signature, shall have affixed thereto the Company's seal or a
facsimile thereof, and shall be attested by the Secretary or an Assistant
Secretary of the Company, either manually or by facsimile signature. The Right
Certificates shall be manually


                                       6.
<PAGE>   10
countersigned by the Rights Agent and shall not be valid for any purpose unless
countersigned. In case any officer of the Company who shall have signed any of
the Right Certificates shall cease to be such officer of the Company before
countersignature by the Rights Agent and issuance and delivery by the Company,
such Right Certificates, nevertheless, may be countersigned by the Rights Agent
and issued and delivered by the Company with the same force and effect as though
the person who signed such Right Certificates had not ceased to be such officer
of the Company; and any Right Certificate may be signed on behalf of the Company
by any person who, at the actual date of the execution of such Right
Certificate, shall be a proper officer of the Company to sign such Right
Certificate, although at the date of the execution of this Agreement any such
person was not such an officer.

      Following the Distribution Date, the Rights Agent will keep or cause to be
kept, at its office designated for such purpose, books for registration and
transfer of the Right Certificates issued hereunder. Such books shall show the
names and addresses of the respective holders of the Right Certificates, the
number of Rights evidenced on its face by each of the Right Certificates and the
date of each of the Right Certificates.

SECTION 6. TRANSFER, SPLIT UP, COMBINATION AND EXCHANGE OF RIGHT CERTIFICATES;
MUTILATED, DESTROYED, LOST OR STOLEN RIGHT CERTIFICATES. Subject to the
provisions of Section 11(a)(ii), Section 14 and Section 24 hereof, at any time
after the Close of Business on the Distribution Date, and at or prior to the
Close of Business on the earlier of the Redemption Date or the Final Expiration
Date, any Right Certificate or Right Certificates may be transferred, split up,
combined or exchanged for another Right Certificate or Right Certificates,
entitling the registered holder to purchase a like number of one one-hundredths
of a Preferred Share as the Right Certificate or Right Certificates surrendered
then entitled such holder to purchase. Any registered holder desiring to
transfer, split up, combine or exchange any Right Certificate or Right
Certificates shall make such request in writing delivered to the Rights Agent,
and shall surrender the Right Certificate or Right Certificates to be
transferred, split up, combined or exchanged at the office of the Rights Agent
designated for such purpose. Neither the Rights Agent nor the Company shall be
obligated to take any action whatsoever with respect to the transfer of any such
surrendered Right Certificate until the registered holder shall have completed
and signed the certificate contained in the form of assignment on the reverse
side of such Right Certificate and shall have provided such additional evidence
of the identity of the Beneficial Owner (or former Beneficial Owner) or
Affiliates or Associates thereof as the Company shall reasonably request.
Thereupon the Rights Agent shall, subject to Section 11(a)(ii), Section 14 and
Section 24 hereof, countersign and deliver to the person entitled thereto a
Right Certificate or Right Certificates, as the case may be, as so requested.
The Company may require payment of a sum sufficient to cover any tax or
governmental charge that may be imposed in connection with any transfer, split
up, combination or exchange of Right Certificates.

      Upon receipt by the Company and the Rights Agent of evidence reasonably
satisfactory to them of the loss, theft, destruction or mutilation of a Right
Certificate, and, in case of loss, theft or destruction, of indemnity or
security reasonably satisfactory to them, and, at the Company's request,
reimbursement to the Company and the Rights Agent of all reasonable expenses
incidental thereto, and upon surrender to the Rights Agent and cancellation of
the Right Certificate if mutilated, the Company will issue, execute and deliver
a new Right Certificate of


                                       7.
<PAGE>   11
like tenor to the Rights Agent for countersignature and delivery to the
registered holder in lieu of the Right Certificate so lost, stolen, destroyed or
mutilated.

      Notwithstanding any other provisions hereof, the Company and the Rights
Agent may amend this Rights Agreement to provide for uncertificated Rights in
addition to or in place of Rights evidenced by Rights Certificates.

SECTION 7. EXERCISE OF RIGHTS; PURCHASE PRICE; EXPIRATION DATE OF RIGHTS.

      (a) The registered holder of any Right Certificate may exercise the Rights
evidenced thereby (except as otherwise provided herein) in whole or in part at
any time after the Distribution Date upon surrender of the Right Certificate,
with the form of election to purchase on the reverse side thereof duly executed,
to the Rights Agent at the office of the Rights Agent designated for such
purpose, together with payment of the Purchase Price for each one one-hundredth
of a Preferred Share (or such other number of shares or other securities) as to
which the Rights are exercised, at or prior to the earliest of (i) the Close of
Business on November 3, 2009 (the "Final Expiration Date"), (ii) the time at
which the Rights are redeemed as provided in Section 23 hereof (the "Redemption
Date"), or (iii) the time at which such Rights are exchanged as provided in
Section 24 hereof.

      (b) The purchase price (the "Purchase Price") for each one one-hundredth
of a Preferred Share pursuant to the exercise of a Right shall initially be $170
and shall be subject to adjustment from time to time as provided in Sections 11
and 13 hereof and shall be payable in lawful money of the United States of
America in accordance with paragraph (c) below.

      (c) Upon receipt of a Right Certificate representing exercisable Rights,
with the form of election to purchase duly executed, accompanied by payment of
the Purchase Price for the shares to be purchased and an amount equal to any
applicable transfer tax required to be paid by the holder of such Right
Certificate in accordance with Section 9 hereof by certified check, cashier's
check, bank draft or money order payable to the order of the Company, the Rights
Agent shall thereupon promptly (i) (A) requisition from any transfer agent for
the Preferred Shares certificates for the number of Preferred Shares to be
purchased and the Company hereby irrevocably authorizes its transfer agent to
comply with all such requests, or (B) if the Company, in its sole discretion,
shall have elected to deposit the Preferred Shares issuable upon exercise of the
Rights hereunder into a depository, requisition from the depositary agent
depositary receipts representing such number of one one-hundredths of a
Preferred Share as are to be purchased (in which case certificates for the
Preferred Shares represented by such receipts shall be deposited by the transfer
agent with the depositary agent) and the Company hereby directs the depositary
agent to comply with such request, (ii) when appropriate, requisition from the
Company the amount of cash to be paid in lieu of issuance of fractional shares
in accordance with Section 14 hereof, (iii) after receipt of such certificates
or depositary receipts, cause the same to be delivered to or upon the order of
the registered holder of such Right Certificate, registered in such name or
names as may be designated by such holder and (iv) when appropriate, after
receipt, deliver such cash to or upon the order of the registered holder of such
Right Certificate. In the event that the Company is obligated to issue
securities of the Company other than Preferred Shares (including Common Shares)
of the Company pursuant to Section 11(a) hereof, the Company will make all


                                       8.
<PAGE>   12
arrangements necessary so that such other securities are available for
distribution by the Rights Agent, if and when appropriate.

      In addition, in the case of an exercise of the Rights by a holder pursuant
to Section 11(a)(ii) hereof, the Rights Agent shall return such Right
Certificate to the registered holder thereof after imprinting, stamping or
otherwise indicating thereon that the rights represented by such Right
Certificate no longer include the rights provided by Section 11(a)(ii) hereof,
and, if fewer than all the Rights represented by such Right Certificate were so
exercised, the Rights Agent shall indicate on the Right Certificate the number
of Rights represented thereby which continue to include the rights provided by
Section 11(a)(ii) hereof.

      (d) In case the registered holder of any Right Certificate shall exercise
fewer than all the Rights evidenced thereby, a new Right Certificate evidencing
Rights equivalent to the Rights remaining unexercised shall be issued by the
Rights Agent to the registered holder of such Right Certificate or to his duly
authorized assigns, subject to the provisions of Section 14 hereof.

      (e) The Company covenants and agrees that it will cause to be reserved and
kept available out of its authorized and unissued Preferred Shares or any
Preferred Shares held in its treasury, the number of Preferred Shares that will
be sufficient to permit the exercise in full of all outstanding Rights in
accordance with this Section 7.

      (f) Notwithstanding anything in this Agreement to the contrary, neither
the Rights Agent nor the Company shall be obligated to undertake any action with
respect to a registered holder upon the occurrence of any purported exercise as
set forth in this Section 7 unless such registered holder shall have (i)
completed and signed the certification following the form of election to
purchase set forth on the reverse side of the Rights Certificate surrendered for
such exercise and (ii) provided such additional evidence of the identity of the
Beneficial Owner (or former Beneficial Owner) or Affiliates or Associates
thereof as the Company shall reasonably request.

SECTION 8. CANCELLATION AND DESTRUCTION OF RIGHT CERTIFICATES. All Right
Certificates surrendered for the purpose of exercise, transfer, split up,
combination or exchange shall, if surrendered to the Company or to any of its
agents, be delivered to the Rights Agent for cancellation or in canceled form,
or, if delivered or surrendered to the Rights Agent, shall be canceled by it,
and no Right Certificates shall be issued in lieu thereof except as expressly
permitted by any of the provisions of this Agreement. The Company shall deliver
to the Rights Agent for cancellation and retirement, and the Rights Agent shall
so cancel and retire, any other Right Certificate purchased or acquired by the
Company otherwise than upon the exercise thereof. The Rights Agent shall deliver
all canceled Right Certificates to the Company approximately one and one-half
years after the cancellation date, or shall, at the written request of the
Company and after any Securities and Exchange Commission-required retention
period, destroy such canceled Right Certificates, and in such case shall deliver
a certificate of destruction thereof to the Company.

SECTION 9. AVAILABILITY OF PREFERRED SHARES. The Company covenants and agrees
that so long as the Preferred Shares (and, after the time a person becomes an
Acquiring Person, Common Shares or any other securities) issuable upon the
exercise of the Rights may be listed


                                       9.
<PAGE>   13
on any national securities exchange or quotation system, the Company shall use
its best efforts to cause, from and after such time as the Rights become
exercisable, all shares reserved for such issuance to be listed on such exchange
or quotation system upon official notice of issuance upon such exercise.

      The Company covenants and agrees that it will take all such action as may
be necessary to ensure that all Preferred Shares (or Common Shares and other
securities, as the case may be) delivered upon exercise of Rights shall, at the
time of delivery of the certificates for such Preferred Shares (subject to
payment of the Purchase Price), be duly and validly authorized and issued and
fully paid and nonassessable shares or other securities.

      The Company further covenants and agrees that it will pay when due and
payable any and all federal and state transfer taxes and charges which may be
payable in respect of the issuance or delivery of the Right Certificates or of
any Preferred Shares upon the exercise of Rights. The Company shall not,
however, be required to pay any transfer tax which may be payable in respect of
any transfer or delivery of Right Certificates to a person other than, or the
issuance or delivery of certificates or depositary receipts for the Preferred
Shares in a name other than that of, the registered holder of the Right
Certificate evidencing Rights surrendered for exercise or to issue or to deliver
any certificates or depositary receipts for Preferred Shares upon the exercise
of any Rights until any such tax shall have been paid (any such tax being
payable by the holder of such Right Certificate at the time of surrender) or
until it has been established to the Company's reasonable satisfaction that no
such tax is due.

      As soon as practicable after the Distribution Date, the Company shall use
its best efforts to:

            (i) prepare and file a registration statement under the Securities
Act of 1933, as amended (the "Act"), with respect to the Rights and the
securities purchasable upon exercise of the Rights on an appropriate form, will
use its best efforts to cause such registration statement to become effective as
soon as practicable after such filing and will use its best efforts to cause
such registration statement to remain effective (with a prospectus at all times
meeting the requirements of the Act) until the Final Expiration Date; and

            (ii) use its best efforts to qualify or register the Rights and the
securities purchasable upon exercise of the Rights under the blue sky laws of
such jurisdictions as may be necessary or appropriate.

SECTION 10. PREFERRED SHARES RECORD DATE. Each person in whose name any
certificate for Preferred Shares or other securities is issued upon the exercise
of Rights shall for all purposes be deemed to have become the holder of record
of the Preferred Shares or other securities represented thereby on, and such
certificate shall be dated, the date upon which the Right Certificate evidencing
such Rights was duly surrendered with the forms of election and certification
duly executed and payment of the Purchase Price (and any applicable transfer
taxes) was made; provided, however, that if the date of such surrender and
payment is a date upon which the Preferred Shares or other


                                      10.
<PAGE>   14
securities transfer books of the Company are closed, such person shall be deemed
to have become the record holder of such shares on, and such certificate shall
be dated, the next succeeding Business Day on which the Preferred Shares or
other securities transfer books of the Company are open. Prior to the exercise
of the Rights evidenced thereby, the holder of a Right Certificate, as such,
shall not be entitled to any rights of a holder of Preferred Shares for which
the Rights shall be exercisable, including, without limitation, the right to
vote, to receive dividends or other distributions or to exercise any preemptive
rights, and shall not be entitled to receive any notice of any proceedings of
the Company, except as provided herein.

SECTION 11. ADJUSTMENT OF PURCHASE PRICE, NUMBER OF SHARES OR NUMBER OF Rights.
The Purchase Price, the number of Preferred Shares covered by each Right and the
number of Rights outstanding are subject to adjustment from time to time as
provided in this Section 11.

      (a)

            (i) In the event the Company shall at any time after the date of
this Agreement (A) declare a dividend on the Preferred Shares payable in
Preferred Shares, (B) subdivide the outstanding Preferred Shares, (C) combine
the outstanding Preferred Shares into a smaller number of Preferred Shares or
(D) issue any shares of its capital stock in a reclassification of the Preferred
Shares (including any such reclassification in connection with a consolidation
or merger in which the Company is the continuing or surviving corporation),
except as otherwise provided in this Section 11(a), the Purchase Price in effect
at the time of the record date for such dividend or of the effective date of
such subdivision, combination or reclassification, and the number and kind of
shares of capital stock issuable on such date, shall be proportionately adjusted
so that the holder of any Right exercised after such time shall be entitled to
receive the aggregate number and kind of shares of capital stock which, if such
Right had been exercised immediately prior to such date and at a time when the
Preferred Shares transfer books of the Company were open, such holder would have
owned upon such exercise and been entitled to receive by virtue of such
dividend, subdivision, combination or reclassification; provided, however, that
in no event shall the consideration to be paid upon the exercise of one Right be
less than the aggregate par value of the shares of capital stock of the Company
issuable upon exercise of one Right. If an event occurs which would require an
adjustment under both Section 11(a)(i) and Section 11(a)(ii) hereof, the
adjustment provided for in this Section 11(a)(i) shall be in addition to, and
shall be made prior to any adjustment required pursuant to Section 11(a)(ii)
hereof.

            (ii) Subject to Section 24 hereof and the provisions of the next
paragraph of this Section 11(a)(ii), in the event any Person shall become an
Acquiring Person, each holder of a Right shall, for a period of 60 days after
the later of such time any Person becomes an Acquiring Person or the effective
date of an appropriate registration statement under the Act pursuant to Section
9 hereof (provided, however that, if at any time prior to the expiration or
termination of the Rights there shall be a temporary restraining order, a
preliminary injunction, an injunction, or temporary suspension by the Board of
Directors, or similar obstacle to exercise of the Rights (the "Injunction")
which prevents exercise of the Rights, a new 60-day period shall commence on the
date the Injunction is removed), have a right to receive, upon exercise thereof
at a price equal to the then current Purchase Price multiplied by the number of
one one-hundredths of a Preferred Share for which a Right is then exercisable,
in accordance with the terms of this Agreement and in lieu of Preferred Shares,
such number of Common Shares as shall equal the result obtained by


                                      11.
<PAGE>   15
(A) multiplying the then current Purchase Price by the number of one
one-hundredths of a Preferred Share for which a Right is then exercisable and
dividing that product by (B) 50% of the then current per share market price of
the Common Shares (determined pursuant to Section 11(d) hereof) on the date such
Person became an Acquiring Person; provided, however, that if the transaction
that would otherwise give rise to the foregoing adjustment is also subject to
the provisions of Section 13 hereof, then only the provisions of Section 13
hereof shall apply and no adjustment shall be made pursuant to this Section
11(a)(ii). In the event that any Person shall become an Acquiring Person and the
Rights shall then be outstanding, the Company shall not take any action which
would eliminate or diminish the benefits intended to be afforded by the Rights.

      Notwithstanding anything in this Agreement to the contrary, from and after
the time any Person becomes an Acquiring Person, any Rights beneficially owned
by (i) such Acquiring Person or an Associate or Affiliate of such Acquiring
Person, (ii) a transferee of such Acquiring Person (or of any such Associate or
Affiliate) who becomes a transferee after the Acquiring Person became such, or
(iii) a transferee of such Acquiring Person (or of any such Associate or
Affiliate) who becomes a transferee prior to or concurrently with the Acquiring
Person's becoming such and receives such Rights pursuant to either (A) a
transfer (whether or not for consideration) from the Acquiring Person to holders
of equity interests in such Acquiring Person or to any Person with whom the
Acquiring Person has any continuing agreement, arrangement or understanding
regarding the transferred Rights or (B) a transfer which the Board of Directors
of the Company has determined is part of a plan, arrangement or understanding
which has as a primary purpose or effect the avoidance of this Section
11(a)(ii), shall become null and void without any further action and no holder
of such Rights shall have any rights whatsoever with respect to such Rights,
whether under any provision of this Agreement or otherwise. The Company shall
use all reasonable efforts to insure that the provisions of this Section
11(a)(ii) and Section 4(b) hereof are complied with, but shall have no liability
to any holder of Right Certificates or other Person as a result of its failure
to make any determinations with respect to an Acquiring Person or its
Affiliates, Associates or transferees hereunder. No Right Certificate shall be
issued at any time upon the transfer of any Rights to an Acquiring Person whose
Rights would be void pursuant to the preceding sentence or any Associate or
Affiliate thereof or to any nominee of such Acquiring Person, Associate or
Affiliate; and any Right Certificate delivered to the Rights Agent for transfer
to an Acquiring Person whose Rights would be void pursuant to the preceding
sentence shall be canceled.

            (iii) In lieu of issuing Common Shares in accordance with Section
11(a)(ii) hereof, the Company may, if a majority of the Board of Directors then
in office determines that such action is necessary or appropriate and not
contrary to the interests of holders of Rights, elect to (and, in the event that
the Board of Directors has not exercised the exchange right contained in Section
24(c) hereof and there are not sufficient treasury shares and authorized but
unissued Common Shares to permit the exercise in full of the Rights in
accordance with the foregoing subparagraph (ii), the Company shall) take all
such action as may be necessary to authorize, issue or pay, upon the exercise of
the Rights, cash (including by way of a reduction of the Purchase Price),
property, Common Shares, other securities or any combination thereof having an
aggregate value equal to the value of the Common Shares which otherwise would
have been issuable pursuant to Section 11(a)(ii) hereof, which aggregate value
shall be determined by a nationally recognized investment banking firm selected
by a majority of the Board of Directors


                                      12.
<PAGE>   16
then in office. For purposes of the preceding sentence, the value of the Common
Shares shall be determined pursuant to Section 11(d) hereof. Any such election
by the Board of Directors must be made within 60 days following the date on
which the event described in Section 11(a)(ii) hereof shall have occurred.
Following the occurrence of the event described in Section 11(a)(ii) hereof, a
majority of the Board of Directors then in office may suspend the exercisability
of the Rights for a period of up to 60 days following the date on which the
event described in Section 11(a)(ii) hereof shall have occurred to the extent
that such directors have not determined whether to exercise their rights of
election under this Section 11(a)(iii). In the event of any such suspension, the
Company shall issue a public announcement stating that the exercisability of the
Rights has been temporarily suspended.

      (b) In case the Company shall fix a record date for the issuance of
rights, options or warrants to all holders of Preferred Shares entitling them
(for a period expiring within 45 calendar days after such record date) to
subscribe for or purchase Preferred Shares (or shares having the same
designations and the powers, preferences and rights, and the qualifications,
limitations and restrictions as the Preferred Shares ("equivalent preferred
shares")) or securities convertible into Preferred Shares or equivalent
preferred shares at a price per Preferred Share or equivalent preferred share
(or having a conversion price per share, if a security convertible into
Preferred Shares or equivalent preferred shares) less than the then current per
share market price of the Preferred Shares (as such term is hereinafter defined)
on such record date, the Purchase Price to be in effect after such record date
shall be determined by multiplying the Purchase Price in effect immediately
prior to such record date by a fraction, the numerator of which shall be the
number of Preferred Shares outstanding on such record date plus the number of
Preferred Shares which the aggregate offering price of the total number of
Preferred Shares and/or equivalent preferred shares so to be offered (and/or the
aggregate initial conversion price of the convertible securities so to be
offered) would purchase at such current market price and the denominator of
which shall be the number of Preferred Shares outstanding on such record date
plus the number of additional Preferred Shares and/or equivalent preferred
shares to be offered for subscription or purchase (or into which the convertible
securities so to be offered are initially convertible); provided, however, that
in no event shall the consideration to be paid upon the exercise of one Right be
less than the aggregate par value of the shares of capital stock of the Company
issuable upon exercise of one Right. In case such subscription price may be paid
in a consideration part or all of which shall be in a form other than cash, the
value of such consideration shall be as determined in good faith by the Board of
Directors of the Company, whose determination shall be described in a statement
filed with the Rights Agent. Preferred Shares owned by or held for the account
of the Company shall not be deemed outstanding for the purpose of any such
computation. Such adjustment shall be made successively whenever such a record
date is fixed; and in the event that such rights, options or warrants are not so
issued, the Purchase Price shall be adjusted to be the Purchase Price which
would then be in effect if such record date had not been fixed.

      (c) In case the Company shall fix a record date for the making of a
distribution to all holders of the Preferred Shares (including any such
distribution made in connection with a consolidation or merger in which the
Company is the continuing or surviving corporation) of evidences of indebtedness
or assets (other than a regular quarterly cash dividend or a dividend payable in
Preferred Shares) or subscription rights or warrants (excluding those referred
to in Section 11(b) hereof), the Purchase Price to be in effect after such
record date shall be


                                      13.
<PAGE>   17
determined by multiplying the Purchase Price in effect immediately prior to such
record date by a fraction, the numerator of which shall be the then current per
share market price of the Preferred Shares (as such term is hereinafter defined)
on such record date, less the fair market value (as determined in good faith by
the Board of Directors of the Company, whose determination shall be described in
a statement filed with the Rights Agent) of the portion of the assets or
evidences of indebtedness so to be distributed or of such subscription rights or
warrants applicable to one Preferred Share and the denominator of which shall be
such current per share market price of the Preferred Shares; provided, however,
that in no event shall the consideration to be paid upon the exercise of one
Right be less than the aggregate par value of the shares of capital stock of the
Company to be issued upon exercise of one Right. Such adjustments shall be made
successively whenever such a record date is fixed; and in the event that such
distribution is not so made, the Purchase Price shall again be adjusted to be
the Purchase Price which would then be in effect if such record date had not
been fixed.

      (d)

            (i) For the purpose of any computation hereunder, the "current per
share market price" of any security (a "Security" for the purpose of this
Section 11(d)(i)) on any date shall be deemed to be the average of the daily
closing prices per share of such Security for the 30 consecutive Trading Days
(as such term is hereinafter defined) immediately prior to such date; provided,
however, that in the event that the current per share market price of the
Security is determined during a period following the announcement by the issuer
of such Security of (A) a dividend or distribution on such Security payable in
shares of such Security or securities convertible into such shares, or (B) any
subdivision, combination or reclassification of such Security or securities
convertible into such shares, or (C) any subdivision, combination or
reclassification of such Security and prior to the expiration of 30 Trading Days
after the ex-dividend date for such dividend or distribution, or the record date
for such subdivision, combination or reclassification, then, and in each such
case, the current per share market price shall be appropriately adjusted to
reflect the current market price per share equivalent of such Security. The
closing price for each day shall be the last sale price, regular way, or, in
case no such sale takes place on such day, the average of the closing bid and
asked prices, regular way, in either case as reported in the principal
consolidated transaction reporting system with respect to securities listed or
admitted to trading on the New York Stock Exchange or, if the Security is not
listed or admitted to trading on the New York Stock Exchange, as reported in the
principal consolidated transaction reporting system with respect to securities
listed on the principal national securities exchange on which the Security is
listed or admitted to trading or as reported on the Nasdaq National Market or,
if the Security is not listed or admitted to trading on any national securities
exchange or reported on the Nasdaq National Market, the last quoted price or, if
not so quoted, the average of the high bid and low asked prices in the
over-the-counter market, as reported by the National Association of Securities
Dealers, Inc. Automated Quotations System ("Nasdaq") or such other system then
in use, or, if on any such date the Security is not quoted by any such
organization, the average of the closing bid and asked prices as furnished by a
professional market maker making a market in the Security selected by the Board
of Directors of the Company or, if on any such date no professional market maker
is making a market in the Security, the price as determined in good faith by the
Board of Directors. The term "Trading Day" shall mean a day on which the
principal national securities exchange on which the Security


                                      14.
<PAGE>   18
is listed or admitted to trading is open for the transaction of business or, if
the Security is not listed or admitted to trading on any national securities
exchange, a Business Day.

            (ii) For the purpose of any computation hereunder, the "current per
share market price" of the Preferred Shares shall be determined in accordance
with the method set forth in Section 11(d)(i) hereof. If the Preferred Shares
are not publicly traded, the "current per share market price" of the Preferred
Shares shall be conclusively deemed to be the current per share market price of
the Common Shares as determined pursuant to Section 11(d)(i) hereof
(appropriately adjusted to reflect any stock split, stock dividend or similar
transaction occurring after the date hereof) multiplied by one hundred. If
neither the Common Shares nor the Preferred Shares are publicly held or so
listed or traded, "current per share market price" shall mean the fair value per
share as determined in good faith by the Board of Directors of the Company,
whose determination shall be described in a statement filed with the Rights
Agent.

      (e) No adjustment in the Purchase Price shall be required unless such
adjustment would require an increase or decrease of at least 1% in the Purchase
Price; provided, however, that any adjustments which by reason of this Section
11(e) are not required to be made shall be carried forward and taken into
account in any subsequent adjustment. All calculations under this Section 11
shall be made to the nearest cent or to the nearest one one-hundredth of a
Preferred Share or one ten-thousandth of any other share or security as the case
may be. Notwithstanding the first sentence of this Section 11(e), any adjustment
required by this Section 11 shall be made no later than the earlier of (i) three
years from the date of the transaction which requires such adjustment or (ii)
the date of the expiration of the right to exercise any Rights.

      (f) If as a result of an adjustment made pursuant to Section 11(a) hereof,
the holder of any Right thereafter exercised shall become entitled to receive
any shares of capital stock of the Company other than Preferred Shares,
thereafter the number of such other shares so receivable upon exercise of any
Right shall be subject to adjustment from time to time in a manner and on terms
as nearly equivalent as practicable to the provisions with respect to the
Preferred Shares contained in Sections 11(a) through 11(c) hereof, inclusive,
and the provisions of Sections 7, 9, 10, 13 and 14 hereof with respect to the
Preferred Shares shall apply on like terms to any such other shares.

      (g) All Rights originally issued by the Company subsequent to any
adjustment made to the Purchase Price hereunder shall evidence the right to
purchase, at the adjusted Purchase Price, the number of one one-hundredths of a
Preferred Share purchasable from time to time hereunder upon exercise of the
Rights, all subject to further adjustment as provided herein.

      (h) Unless the Company shall have exercised its election as provided in
Section 11(i) hereof, upon each adjustment of the Purchase Price as a result of
the calculations made in Section 11(b) and Section 11(c) hereof, each Right
outstanding immediately prior to the making of such adjustment shall thereafter
evidence the right to purchase, at the adjusted Purchase Price, that number of
one one-hundredths of a Preferred Share (calculated to the nearest one
one-millionth of a Preferred Share) obtained by (i) multiplying (x) the number
of one one-hundredths of a Preferred Share covered by a Right immediately prior
to this adjustment by (y) the Purchase Price in effect immediately prior to such
adjustment of the Purchase Price and (ii) dividing the


                                      15.
<PAGE>   19
product so obtained by the Purchase Price in effect immediately after such
adjustment of the Purchase Price.

      (i) The Company may elect on or after the date of any adjustment of the
Purchase Price to adjust the number of Rights, in substitution for any
adjustment in the number of one one-hundredths of a Preferred Share purchasable
upon the exercise of a Right. Each of the Rights outstanding after such
adjustment of the number of Rights shall be exercisable for the number of one
one-hundredths of a Preferred Share for which a Right was exercisable
immediately prior to such adjustment. Each Right held of record prior to such
adjustment of the number of Rights shall become that number of Rights
(calculated to the nearest one ten-thousandth) obtained by dividing the Purchase
Price in effect immediately prior to adjustment of the Purchase Price by the
Purchase Price in effect immediately after adjustment of the Purchase Price. The
Company shall make a public announcement of its election to adjust the number of
Rights, indicating the record date for the adjustment, and, if known at the
time, the amount of the adjustment to be made. This record date may be the date
on which the Purchase Price is adjusted or any day thereafter, but, if the Right
Certificates have been issued, shall be at least 10 days later than the date of
the public announcement. If Right Certificates have been issued, upon each
adjustment of the number of Rights pursuant to this Section 11(i), the Company
shall, as promptly as practicable, cause to be distributed to holders of record
of Right Certificates on such record date Right Certificates evidencing, subject
to Section 14 hereof, the additional Rights to which such holders shall be
entitled as a result of such adjustment, or, at the option of the Company, shall
cause to be distributed to such holders of record in substitution and
replacement for the Right Certificates held by such holders prior to the date of
adjustment, and upon surrender thereof, if required by the Company, new Right
Certificates evidencing all the Rights to which such holders shall be entitled
after such adjustment. Right Certificates so to be distributed shall be issued,
executed and countersigned in the manner provided for herein and shall be
registered in the names of the holders of record of Right Certificates on the
record date specified in the public announcement.

      (j) Irrespective of any adjustment or change in the Purchase Price or the
number of one one-hundredths of a Preferred Share issuable upon the exercise of
the Rights, the Right Certificates theretofore and thereafter issued may
continue to express the Purchase Price and the number of one one-hundredths of a
Preferred Share which were expressed in the initial Right Certificates issued
hereunder.

      (k) Before taking any action that would cause an adjustment reducing the
Purchase Price below one one-hundredth of the then par value, if any, of the
Preferred Shares issuable upon exercise of the Rights, the Company shall take
any corporate action which may, in the opinion of its counsel, be necessary in
order that the Company may validly and legally issue fully paid and
nonassessable Preferred Shares at such adjusted Purchase Price.

      (l) In any case in which this Section 11 shall require that an adjustment
in the Purchase Price be made effective as of a record date for a specified
event, the Company may elect to defer until the occurrence of such event the
issuing to the holder of any Right exercised after such record date of the
Preferred Shares and other capital stock or securities of the Company, if any,
issuable upon such exercise on the basis of the Purchase Price in effect prior
to such adjustment; provided, however, that the Company shall deliver to such
holder a due bill or


                                      16.
<PAGE>   20
other appropriate instrument evidencing such holder's right to receive such
additional shares upon the occurrence of the event requiring such adjustment.

      (m) The Company covenants and agrees that, after the Distribution Date, it
will not, except as permitted by Section 23 or Section 27 hereof, take (or
permit any Subsidiary to take) any action the purpose of which is to, or if at
the time such action is taken it is reasonably foreseeable that the effect of
such action is to, materially diminish or eliminate the benefits intended to be
afforded by the Rights. Any such action taken by the Company during any period
after any Person becomes an Acquiring Person but prior to the Distribution Date
shall be null and void unless such action could be taken under this Section
11(m) from and after the Distribution Date.

      (n) Anything in this Section 11 to the contrary notwithstanding, the
Company shall be entitled to make such reductions in the Purchase Price, in
addition to those adjustments expressly required by this Section 11, as and to
the extent that it in its sole discretion shall determine to be advisable in
order that any consolidation or subdivision of the Preferred Shares, issuance
wholly for cash of any Preferred Shares at less than the current market price,
issuance wholly for cash of Preferred Shares or securities which by their terms
are convertible into or exchangeable for Preferred Shares, dividends on
Preferred Shares payable in Preferred Shares or issuance of rights, options or
warrants referred to hereinabove in Section 11(b), hereafter made by the Company
to holders of its Preferred Shares shall not be taxable to such stockholders.

      (o) In the event that at any time after the date of this Agreement and
prior to the Distribution Date, the Company shall (i) declare or pay any
dividend on the Common Shares payable in Common Shares or (ii) effect a
subdivision, combination or consolidation of the Common Shares (by
reclassification or otherwise than by payment of dividends in Common Shares)
into a greater or lesser number of Common Shares, then in any such case (A) the
number of one one-hundredths of a Preferred Share purchasable after such event
upon proper exercise of each Right shall be determined by multiplying the number
of one one-hundredths of a Preferred Share so purchasable immediately prior to
such event by a fraction, the numerator of which is the number of Common Shares
outstanding immediately before such event and the denominator of which is the
number of Common Shares outstanding immediately after such event, and (B) each
Common Share outstanding immediately after such event shall have issued with
respect to it that number of Rights which each Common Share outstanding
immediately prior to such event had issued with respect to it. The adjustments
provided for in this Section 11(o) shall be made successively whenever such a
dividend is declared or paid or such a subdivision, combination or consolidation
is effected.

      (p) The exercise of Rights under Section 11(a)(ii) hereof shall only
result in the loss of rights under Section 11(a)(ii) hereof to the extent so
exercised and shall not otherwise affect the rights represented by the Rights
under this Agreement, including the rights represented by Section 13 hereof.

SECTION 12. CERTIFICATE OF ADJUSTED PURCHASE PRICE OR NUMBER OF SHARES. Whenever
an adjustment is made as provided in Sections 11 and 13 hereof, the Company
shall promptly (a) prepare a certificate setting forth such adjustment, and a
brief statement of the facts accounting for such adjustment, (b) file with the
Rights Agent and with each transfer agent for


                                      17.
<PAGE>   21
the Common Shares or the Preferred Shares a copy of such certificate and (c)
mail a brief summary thereof to each holder of a Right Certificate in accordance
with Section 25 hereof. The Rights Agent shall be fully protected in relying on
any such certificate and on any adjustment therein contained and shall not be
deemed to have knowledge of any adjustment unless and until it shall have
received such certificate.

SECTION 13. CONSOLIDATION, MERGER OR SALE OR TRANSFER OF ASSETS OR EARNING
POWER.

      (a) In the event that, following the Shares Acquisition Date or, if a
Transaction is proposed, the Distribution Date, directly or indirectly (x) the
Company shall consolidate with, or merge with and into, any Interested
Stockholder, or if in such merger or consolidation all holders of Common Stock
are not treated alike, any other Person, (y) any Interested Person, or if in
such merger or consolidation all holders of Common Stock are not treated alike,
any other Person shall consolidate with the Company, or merge with and into the
Company, and the Company shall be the continuing or surviving corporation of
such merger (other than, in the case of either transaction described in (x) or
(y), a merger or consolidation which would result in all of the voting power
represented by the securities of the Company outstanding immediately prior
thereto continuing to represent (either by remaining outstanding or by being
converted into securities of the surviving entity) all of the voting power
represented by the securities of the Company or such surviving entity
outstanding immediately after such merger or consolidation and the holders of
such securities not having changed as a result of such merger or consolidation),
or (z) the Company shall sell, mortgage or otherwise transfer (or one or more of
its subsidiaries shall sell, mortgage or otherwise transfer), in one or more
transactions, assets or earning power aggregating more than 50% of the assets or
earning power of the Company and its subsidiaries (taken as a whole) to any
Interested Stockholder or Stockholders, or if in such transaction all holders of
Common Stock are not treated alike, any other Person, (other than the Company or
any Subsidiary of the Company in one or more transactions each of which
individually and the aggregate does not violate Section 13(d) hereof) then, and
in each such case, proper provision shall be made so that (i) each holder of a
Right, subject to Section 11(a)(ii) hereof, shall have the right to receive,
upon the exercise thereof at a price equal to the then current Purchase Price
multiplied by the number of one one-hundredths of a Preferred Share for which a
Right is then exercisable in accordance with the terms of this Agreement and in
lieu of Preferred Shares, such number of freely tradeable Common Shares of the
Principal Party (as such term is hereinafter defined), free and clear of liens,
rights of call or first refusal, encumbrances or other adverse claims, as shall
be equal to the result obtained by (A) multiplying the then current Purchase
Price by the number of one one-hundredths of a Preferred Share for which a Right
is then exercisable (without taking into account any adjustment previously made
pursuant to Section 11(a)(ii) hereof) and dividing that product by (B) 50% of
the then current per share market price of the Common Shares of such Principal
Party (determined pursuant to Section 11(d) hereof) on the date of consummation
of such consolidation, merger, sale or transfer; (ii) such Principal Party shall
thereafter be liable for, and shall assume, by virtue of such consolidation,
merger, sale or transfer, all the obligations and duties of the Company pursuant
to this Agreement; (iii) the term "Company" shall thereafter be deemed to refer
to such Principal Party, it being specifically intended that the provisions of
Section 11 hereof shall apply to such Principal Party; and (iv) such Principal
Party shall take such steps (including, but not limited to, the reservation of a
sufficient number of shares of its Common Shares in accordance with Section 9
hereof) in


                                      18.
<PAGE>   22
connection with such consummation as may be necessary to assure that the
provisions hereof shall thereafter be applicable, as nearly as reasonably may
be, in relation to its Common Shares thereafter deliverable upon the exercise of
the Rights.

      (b) "Principal Party" shall mean:

            (i) in the case of any transaction described in clause (x) or (y) of
the first sentence of Section 13(a) hereof, the Person that is the issuer of any
securities into which Common Shares are converted in such merger or
consolidation, and if no securities are so issued, the Person that is the other
party to the merger or consolidation (or, if applicable, the Company, if it is
the surviving corporation); and

            (ii) in the case of any transaction described in (z) of the first
sentence of Section 13(a) hereof, the Person that is the party receiving the
greatest portion of the assets or earning power transferred pursuant to such
transaction or transactions;

provided, however, that in any case, (1) if the Common Shares of such Person are
not at such time and have not been continuously over the preceding 12-month
period registered under Section 12 of the Exchange Act, and such Person is a
direct or indirect subsidiary or Affiliate of another Person the Common Shares
of which are and have been so registered, "Principal Party" shall refer to such
other Person; (2) if such Person is a subsidiary, directly or indirectly, or
Affiliate of more than one Person, the Common Shares of two or more of which are
and have been so registered, "Principal Party" shall refer to whichever of such
Persons is the issuer of the Common Shares having the greatest aggregate market
value; and (3) if such Person is owned, directly or indirectly, by a joint
venture formed by two or more Persons that are not owned, directly or
indirectly, by the same Person, the rules set forth in (1) and (2) above shall
apply to each of the chains of ownership having an interest in such joint
venture as if such party were a "subsidiary" of both or all of such joint
venturers and the Principal Parties in each such chain shall bear the
obligations set forth in this Section 13 in the same ratio as their direct or
indirect interests in such Person bear to the total of such interests.

      (c) The Company shall not consummate any such consolidation, merger, sale
or transfer unless the Principal Party shall have a sufficient number of
authorized Common Shares that have not been issued or reserved for issuance to
permit the exercise in full of the Rights in accordance with this Section 13 and
unless prior thereto the Company and each Principal Party and each other Person
who may become a Principal Party as a result of such consolidation, merger, sale
or transfer shall have (i) executed and delivered to the Rights Agent a
supplemental agreement providing for the terms set forth in paragraphs (a) and
(b) of this Section 13 and (ii) prepared, filed and had declared and remain
effective a registration statement under the Act on the appropriate form with
respect to the Rights and the securities exercisable upon exercise of the Rights
and further providing that, as soon as practicable after the date of any
consolidation, merger, sale or transfer of assets mentioned in paragraph (a) of
this Section 13, the Principal Party at its own expense will:

            (i) cause the registration statement under the Act with respect to
the Rights and the securities purchasable upon exercise of the Rights on an
appropriate form to remain


                                      19.
<PAGE>   23
effective (with a prospectus at all times meeting the requirements of the Act)
until the Final Expiration Date;

            (ii) use its best efforts to qualify or register the Rights and the
securities purchasable upon exercise of the Rights under the blue sky laws of
such jurisdictions as may be necessary or appropriate;

            (iii) list the Rights and the securities purchasable upon exercise
of the Rights on each national securities exchange on which the Common Shares
were listed prior to the consummation of such consolidation, merger, sale or
transfer of assets or on the Nasdaq National Market if the Common Shares were
listed on the Nasdaq National Market or, if the Common Shares were not listed on
a national securities exchange or the Nasdaq National Market prior to the
consummation of such consolidation, merger, sale or transfer of assets, on a
national securities exchange or the Nasdaq National Market; and

            (iv) deliver to holders of the Rights historical financial
statements for the Principal Party and each of its Affiliates which comply in
all material respects with the requirements for registration on Form 10 under
the Exchange Act.

      The provisions of this Section 13 shall similarly apply to successive
mergers or consolidations or sales or other transfers.

      (d) After the Distribution Date, the Company covenants and agrees that it
shall not (i) consolidate with, (ii) merge with or into, or (iii) sell or
transfer to, in one or more transactions, assets or earning power aggregating
more than 50% of the assets or earning power of the Company and its subsidiaries
taken as a whole, any other Person (other than a Subsidiary of the Company in a
transaction which does not violate Section 11(m) hereof), if (x) at the time of
or after such consolidation, merger or sale there are any charter or bylaw
provisions or any rights, warrants or other instruments or securities
outstanding, agreements in effect or any other action taken which would diminish
or otherwise eliminate the benefits intended to be afforded by the Rights or (y)
prior to, simultaneously with or immediately after such consolidation, merger or
sale, the stockholders of the Person who constitutes, or would constitute, the
"Principal Party" for purposes of Section 13(a) hereof shall have received a
distribution of Rights previously owned by such Person or any of its Affiliates
and Associates. The Company shall not consummate any such consolidation, merger,
sale or transfer unless prior thereto the Company and such other Person shall
have executed and delivered to the Rights Agent a supplemental agreement
evidencing compliance with this Section 13(d).

SECTION 14. FRACTIONAL RIGHTS AND FRACTIONAL SHARES.

      (a) The Company shall not be required to issue fractions of Rights or to
distribute Right Certificates which evidence fractional Rights. In lieu of such
fractional Rights, there shall be paid to the registered holders of the Right
Certificates with regard to which such fractional Rights would otherwise be
issuable, an amount in cash equal to the same fraction of the current market
value of a whole Right. For the purposes of this Section 14(a), the current
market value of a whole Right shall be the closing price of the Rights for the
Trading Day immediately prior to the date on which such fractional Rights would
have been otherwise issuable. The closing price


                                      20.
<PAGE>   24
for any day shall be the last sale price, regular way, or, in case no such sale
takes place on such day, the average of the closing bid and asked prices,
regular way, in either case as reported in the principal consolidated
transaction reporting system with respect to securities listed or admitted to
trading on the New York Stock Exchange or, if the Rights are not listed or
admitted to trading on the New York Stock Exchange, as reported in the principal
consolidated transaction reporting system with respect to securities listed on
the principal national securities exchange on which the Rights are listed or
admitted to trading or as reported on the Nasdaq National Market or, if the
Rights are not listed or admitted to trading on any national securities exchange
or reported on the Nasdaq National Market, the last quoted price or, if not so
quoted, the average of the high bid and low asked prices in the over-the-counter
market, as reported by Nasdaq or such other system then in use or, if on any
such date the Rights are not quoted by any such organization, the average of the
closing bid and asked prices as furnished by a professional market maker making
a market in the Rights selected by the Board of Directors of the Company. If on
any such date no such market maker is making a market in the Rights, the fair
value of the Rights on such date as determined in good faith by the Board of
Directors of the Company shall be used.

      (b) The Company shall not be required to issue fractions of Preferred
Shares (other than fractions which are integral multiples of one one-hundredth
of a Preferred Share) upon exercise of the Rights or to distribute certificates
which evidence fractional Preferred Shares (other than fractions which are
integral multiples of one one-hundredth of a Preferred Share). Fractions of
Preferred Shares in integral multiples of one one-hundredth of a Preferred Share
may, at the election of the Company, be evidenced by depositary receipts;
provided, however, that holders of such depositary receipts shall have all of
the designations and the powers, preferences and rights, and the qualifications,
limitations and restrictions to which they are entitled as beneficial owners of
the Preferred Shares represented by such depositary receipts. In lieu of
fractional Preferred Shares that are not integral multiples of one one-hundredth
of a Preferred Share, the Company shall pay to the registered holders of Right
Certificates at the time such Rights are exercised as herein provided an amount
in cash equal to the same fraction of the current market value of one Preferred
Share. For the purposes of this Section 14(b), the current market value of a
Preferred Share shall be the current per share market price of the Preferred
Shares (as determined pursuant to the second sentence of Section 11(d)(i)
hereof) for the Trading Day immediately prior to the date of such exercise (or,
if not publicly traded, in accordance with Section 11(d)(ii) hereof).

      (c) Following the occurrence of one of the transactions or events
specified in Section 11 hereof giving rise to the right to receive Common
Shares, capital stock equivalents (other than Preferred Shares) or other
securities upon the exercise of a Right, the Company shall not be required to
issue fractions of Common Shares or units of such Common Shares, capital stock
equivalents or other securities upon exercise of the Rights or to distribute
certificates which evidence fractional Common Shares, capital stock equivalents
or other securities. In lieu of fractional Common Shares, capital stock
equivalents or other securities, the Company shall pay to the registered holders
of Right Certificates at the time such Rights are exercised as herein provided
an amount in cash equal to the same fraction of the current market value of one
Common Share or unit of such Common Shares, capital stock equivalents or other
securities. For purposes of this Section 14(c), the current market value shall
be the current per share market price (as determined pursuant to Section
11(d)(i) hereof) for the Trading Day immediately prior


                                      21.
<PAGE>   25
to the date of such exercise and, if such capital stock equivalent is not
traded, each such capital stock equivalent shall have the value of one
one-hundredth of a Preferred Share.

      (d) The holder of a Right by the acceptance of the Right expressly waives
his right to receive any fractional Rights or any fractional shares upon
exercise of a Right (except as provided above).

SECTION 15. RIGHTS OF ACTION. All rights of action in respect of this Agreement,
excepting the rights of action given to the Rights Agent under Sections 18 and
20 hereof, are vested in the respective registered holders of the Right
Certificates (and, prior to the Distribution Date, the registered holders of the
Common Shares) and any registered holder of any Right Certificate (or, prior to
the Distribution Date, of the Common Shares), without the consent of the Rights
Agent or of the holder of any other Right Certificate (or, prior to the
Distribution Date, of the Common Shares), may, in his own behalf and for his own
benefit, enforce, and may institute and maintain any suit, action or proceeding
against the Company to enforce, or otherwise act in respect of, his right to
exercise the Rights evidenced by such Right Certificate in the manner provided
in such Right Certificate and in this Agreement. Without limiting the foregoing
or any remedies available to the holders of Rights, it is specifically
acknowledged that the holders of Rights would not have an adequate remedy at law
for any breach of this Agreement and will be entitled to specific performance of
the obligations under, and injunctive relief against actual or threatened
violations of the obligations of any Person subject to, this Agreement. Holders
of Rights shall be entitled to recover the reasonable costs and expenses,
including attorneys fees, incurred by them in any action to enforce the
provisions of this Agreement.

SECTION 16. AGREEMENT OF RIGHT HOLDERS. Every holder of a Right, by accepting
the same, consents and agrees with the Company and the Rights Agent and with
every other holder of a Right that:

      (a) prior to the Distribution Date, the Rights will be transferable only
in connection with the transfer of the Common Shares;

      (b) after the Distribution Date, the Right Certificates are transferable
(subject to the provisions of this Rights Agreement) only on the registry books
of the Rights Agent if surrendered at the principal office of the Rights Agent,
duly endorsed or accompanied by a proper instrument of transfer; and

      (c) the Company and the Rights Agent may deem and treat the person in
whose name the Right Certificate (or, prior to the Distribution Date, the
associated Common Shares certificate) is registered as the absolute owner
thereof and of the Rights evidenced thereby (notwithstanding any notations of
ownership or writing on the Right Certificates or the associated Common Shares
certificate made by anyone other than the Company or the Rights Agent) for all
purposes whatsoever, and neither the Company nor the Rights Agent shall be
affected by any notice to the contrary.

SECTION 17. RIGHT CERTIFICATE HOLDER NOT DEEMED A STOCKHOLDER. No holder, as
such, of any Right Certificate shall be entitled to vote, receive dividends or
be deemed for any purpose the holder of the Preferred Shares or any other
securities of the Company which


                                      22.
<PAGE>   26
may at any time be issuable on the exercise of the Rights represented thereby,
nor shall anything contained herein or in any Right Certificate be construed to
confer upon the holder of any Right Certificate, as such, any of the rights of a
stockholder of the Company or any right to vote for the election of directors or
upon any matter submitted to stockholders at any meeting thereof, or to give or
withhold consent to any corporate action, or to receive notice of meetings or
other actions affecting stockholders (except as provided in Section 25 hereof),
or to receive dividends or subscription rights, or otherwise, until the Right or
Rights evidenced by such Right Certificate shall have been exercised in
accordance with the provisions hereof.

SECTION 18. CONCERNING THE RIGHTS AGENT. The Company agrees to pay to the Rights
Agent reasonable compensation for all services rendered by it hereunder and,
from time to time, on demand of the Rights Agent, its reasonable expenses and
counsel fees and other disbursements incurred in the administration and
execution of this Agreement and the exercise and performance of its duties
hereunder. The Company also agrees to indemnify the Rights Agent for, and to
hold it harmless against, any loss, liability, or expense, incurred without
negligence, bad faith or willful misconduct on the part of the Rights Agent, for
anything done or omitted by the Rights Agent in connection with the acceptance
and administration of this Agreement, including the costs and expenses of
defending against any claim of liability in the premises. The indemnity provided
herein shall survive the expiration of the Rights and the termination of this
Agreement.

      The Rights Agent shall be protected and shall incur no liability for, or
in respect of any action taken, suffered or omitted by it in connection with,
its administration of this Agreement in reliance upon any Right Certificate or
certificate for the Preferred Shares or Common Shares or for other securities of
the Company, instrument of assignment or transfer, power of attorney,
endorsement, affidavit, letter, notice, direction, consent, certificate,
statement, or other paper or document believed by it to be genuine and to be
signed, executed and, where necessary, verified or acknowledged, by the proper
person or persons, or otherwise upon the advice of counsel as set forth in
Section 20 hereof. In no case will the Rights Agent be liable for special,
indirect, incidental or consequential or consequential loss or damage at any
kind whatsoever (including but not limited to lost profits), even if the Rights
Agent has been advised of such loss or damage.

SECTION 19. MERGER OR CONSOLIDATION OR CHANGE OF NAME OF RIGHTS AGENT. Any
corporation into which the Rights Agent or any successor Rights Agent may be
merged or with which it may be consolidated, or any corporation resulting from
any merger or consolidation to which the Rights Agent or any successor Rights
Agent shall be a party, or any corporation succeeding to the shareholder
services or corporate trust business of the Rights Agent or any successor Rights
Agent, shall be the successor to the Rights Agent under this Agreement without
the execution or filing of any paper or any further act on the part of any of
the parties hereto, provided that such corporation would be eligible for
appointment as a successor Rights Agent under the provisions of Section 21
hereof. In case at the time such successor Rights Agent shall succeed to the
agency created by this Agreement any of the Right Certificates shall have been
countersigned but not delivered, any such successor Rights Agent may adopt the
countersignature of the predecessor Rights Agent and deliver such Right
Certificates so countersigned; and in case at that time any of the Right
Certificates shall not have been countersigned, any successor Rights Agent may
countersign such Right Certificates either in the name of the predecessor Rights
Agent or in the name of the successor Rights Agent; and in


                                      23.
<PAGE>   27
all such cases such Right Certificates shall have the full force provided in the
Right Certificates and in this Agreement.

      In case at any time the name of the Rights Agent shall be changed and at
such time any of the Right Certificates shall have been countersigned but not
delivered, the Rights Agent may adopt the countersignature under its prior name
and deliver Right Certificates so countersigned; and in case at that time any of
the Right Certificates shall not have been countersigned, the Rights Agent may
countersign such Right Certificates either in its prior name or in its changed
name; and in all such cases such Right Certificates shall have the full force
provided in the Right Certificates and in this Agreement.

SECTION 20. DUTIES OF RIGHTS AGENT. The Rights Agent undertakes the duties and
obligations imposed by this Agreement upon the following terms and conditions,
by all of which the Company and the holders of Right Certificates, by their
acceptance thereof, shall be bound:

      (a) The Rights Agent may consult with legal counsel of its choice (who may
be legal counsel for the Company), and the opinion of such counsel shall be full
and complete authorization and protection to the Rights Agent as to any action
taken or omitted by it in good faith and in accordance with such opinion.

      (b) Whenever in the performance of its duties under this Agreement the
Rights Agent shall deem it necessary or desirable that any fact or matter be
proved or established by the Company prior to taking or suffering any action
hereunder, such fact or matter (unless other evidence in respect thereof be
herein specifically prescribed) may be deemed to be conclusively proved and
established by a certificate signed by any one of the Chairman of the Board, the
Chief Executive Officer, the President, the Chief Financial Officer, any Vice
President, the Treasurer or the Secretary of the Company and delivered to the
Rights Agent; and such certificate shall be full authorization to the Rights
Agent for any action taken or suffered in good faith by it under the provisions
of this Agreement in reliance upon such certificate.

      (c) The Rights Agent shall be liable hereunder to the Company and any
other Person only for its own negligence, bad faith or willful misconduct.

      (d) The Rights Agent shall not be liable for or by reason of any of the
statements of fact or recitals contained in this Agreement or in the Right
Certificates (except its countersignature thereof) or be required to verify the
same, but all such statements and recitals are and shall be deemed to have been
made by the Company only.

      (e) The Rights Agent shall not be under any responsibility in respect of
the validity of this Agreement or the execution and delivery hereof (except the
due execution hereof by the Rights Agent) or in respect of the validity or
execution of any Right Certificate (except its countersignature thereof); nor
shall it be responsible for any breach by the Company of any covenant or
condition contained in this Agreement or in any Right Certificate; nor shall it
be responsible for any change in the exercisability of the Rights (including the
Rights becoming void pursuant to Section 11(a)(ii) hereof) or any adjustment in
the terms of the Rights (including the manner, method or amount thereof)
provided for in Sections 3, 11, 13, 23 or 24 hereof, or the ascertaining of the
existence of facts that would require any such change or adjustment (except


                                      24.
<PAGE>   28
with respect to the exercise of Rights evidenced by Right Certificates after
receipt of a certificate pursuant to Section 12 hereof describing such change or
adjustment); nor shall it by any act hereunder be deemed to make any
representation or warranty as to the authorization or reservation of any
Preferred Shares to be issued pursuant to this Agreement or any Right
Certificate or as to whether any Preferred Shares will, when issued, be validly
authorized and issued, fully paid and nonassessable.

      (f) The Company agrees that it will perform, execute, acknowledge and
deliver or cause to be performed, executed, acknowledged and delivered all such
further and other acts, instruments and assurances as may reasonably be required
by the Rights Agent for the carrying out or performing by the Rights Agent of
the provisions of this Agreement.

      (g) The Rights Agent is hereby authorized and directed to accept
instructions with respect to the performance of its duties hereunder from any
one of the Chairman of the Board, the Chief Executive Officer, the President,
the Chief Financial Officer, any Vice President, the Secretary or the Treasurer
of the Company, and to apply to such officers for advice or instructions in
connection with its duties, and it shall not be liable for any action taken or
suffered by it in good faith in accordance with instructions of any such officer
or for any delay in acting while waiting for those instructions. Any application
by the Rights Agent for written instructions from the Company may, at the option
of the Rights Agent, set forth in writing any action proposed to be taken or
omitted by the Rights Agent with respect to its duties or obligations under this
Agreement and the date on and/or after which such action shall be taken or
omitted and the Rights Agent shall not be liable for any action taken or omitted
in accordance with a proposal included in any such application on or after the
date specified therein (which date shall not be less than three Business Days
after the date indicated in such application unless any such officer shall have
consented in writing to an earlier date) unless, prior to taking or omitting any
such action, the Rights Agent has received written instructions in response to
such application specifying the action to be taken or omitted.

      (h) The Rights Agent and any stockholder, director, officer or employee of
the Rights Agent may buy, sell or deal in any of the Rights or other securities
of the Company or become pecuniarily interested in any transaction in which the
Company may be interested, or contract with or lend money to the Company or
otherwise act as fully and freely as though it were not Rights Agent under this
Agreement. Nothing herein shall preclude the Rights Agent from acting in any
other capacity for the Company or for any other legal entity.

      (i) The Rights Agent may execute and exercise any of the rights or powers
hereby vested in it or perform any duty hereunder either itself or by or through
its attorneys or agents, and the Rights Agent shall not be answerable or
accountable for any act, default, neglect or misconduct of any such attorneys or
agents or for any loss to the Company resulting from any such act, default,
neglect or misconduct, provided reasonable care was exercised in the selection
and continued employment thereof.

      (j) No provision of this Agreement shall require the Rights Agent to
expend or risk its own funds or otherwise incur any financial liability in the
performance of any of its duties hereunder or in the exercise of its rights if
there shall be reasonable grounds for believing that


                                      25.
<PAGE>   29
repayment of such funds or adequate indemnification against such risk or
liability is not reasonably assured to it.

      (k) If, with respect to any Right Certificate surrendered to the Rights
Agent for exercise or transfer, the certificate attached to the form of
assignment or form of election to purchase, as the case may be, has not been
executed, the Rights Agent shall not take any further action with respect to
such requested exercise of transfer without first consulting with the Company.

SECTION 21. CHANGE OF RIGHTS AGENT. The Rights Agent or any successor Rights
Agent may resign and be discharged from its duties under this Agreement upon 30
days' notice in writing mailed to the Company and to each transfer agent for the
Common Shares or Preferred Shares by registered or certified mail, and to the
holders of the Right Certificates by first-class mail. The Company may remove
the Rights Agent or any successor Rights Agent upon 30 days' notice in writing,
mailed to the Rights Agent or successor Rights Agent, as the case may be, and to
each transfer agent for the Common Shares or Preferred Shares by registered or
certified mail, and to the holders of the Right Certificates by first-class
mail. If the Rights Agent shall resign or be removed or shall otherwise become
incapable of acting, the Company shall appoint a successor to the Rights Agent.
If the Company shall fail to make such appointment within a period of 30 days
after giving notice of such removal or after it has been notified in writing of
such resignation or incapacity by the resigning or incapacitated Rights Agent or
by the holder of a Right Certificate (who shall, with such notice, submit his
Right Certificate for inspection by the Company), then the registered holder of
any Right Certificate may apply to any court of competent jurisdiction for the
appointment of a new Rights Agent. Any successor Rights Agent, whether appointed
by the Company or by such a court, shall be either (a) a corporation business
trust or limited liability company organized and doing business under the laws
of the United States or of any other state of the United States which is
authorized under such laws to exercise corporate trust or stock transfer powers
and is subject to supervision or examination by federal or state authority and
which has at the time of its appointment as Rights Agent a combined capital and
surplus of at least $50 million or (b) a direct or indirect wholly owned
subsidiary of such an entity or its wholly-owning parent. After appointment, the
successor Rights Agent shall be vested with the same powers, rights, duties and
responsibilities as if it had been originally named as Rights Agent without
further act or deed; but the predecessor Rights Agent shall deliver and transfer
to the successor Rights Agent any property at the time held by it hereunder, and
execute and deliver any further assurance, conveyance, act or deed necessary for
the purpose. Not later than the effective date of any such appointment the
Company shall file notice thereof in writing with the predecessor Rights Agent
and each transfer agent for the Common Shares or Preferred Shares, and mail a
notice thereof in writing to the registered holders of the Right Certificates.
Failure to give any notice provided for in this Section 21, however, or any
defect therein, shall not affect the legality or validity of the resignation or
removal of the Rights Agent or the appointment of the successor Rights Agent, as
the case may be.

SECTION 22. ISSUANCE OF NEW RIGHT CERTIFICATES. Notwithstanding any of the
provisions of this Agreement or of the Rights to the contrary, the Company may,
at its option, issue new Right Certificates evidencing Rights in such form as
may be approved by its Board of Directors to reflect any adjustment or change in
the Purchase Price and the number or kind or class of shares or other securities
or property purchasable under the Right Certificates made in


                                      26.
<PAGE>   30
accordance with the provisions of this Agreement. In addition, in connection
with the issuance or sale of Common Shares following the Distribution Date and
prior to the earlier of the Redemption Date and the Final Expiration Date, the
Company (a) shall with respect to Common Shares so issued or sold pursuant to
the exercise of stock options or under any employee plan or arrangement in
existence prior to the Distribution Date, or upon the exercise, conversion or
exchange of securities, notes or debentures issued by the Company and in
existence prior to the Distribution Date, and (b) may, in any other case, if
deemed necessary or appropriate by the Board of Directors of the Company, issue
Right Certificates representing the appropriate number of Rights in connection
with such issuance or sale; provided, however, that (i) the Company shall not be
obligated to issue any such Right Certificates if, and to the extent that, the
Company shall be advised by counsel that such issuance would create a
significant risk of material adverse tax consequences to the Company or the
Person to whom such Right Certificate would be issued, and (ii) no Right
Certificate shall be issued if, and to the extent that, appropriate adjustment
shall otherwise have been made in lieu of the issuance thereof.

SECTION 23. REDEMPTION.

      (a) The Rights may be redeemed by action of the Board of Directors
pursuant to Section 23(b) hereof and shall not be redeemed in any other manner.

      (b)

            (i) The Board of Directors of the Company may, at its option, at any
time prior to the earlier of such time as any Person becoming an Acquiring
Person or the Final Expiration Date, redeem all but not less than all of the
then outstanding Rights at a redemption price of $0.001 per Right, appropriately
adjusted to reflect any stock split, stock dividend or similar transaction
occurring after the date hereof (such redemption price being hereinafter
referred to as the "Redemption Price"), and the Company may, at its option, pay
the Redemption Price in Common Shares (based on the "current per-share market
price," as such term is defined in Section 11(d) hereof, of the Common Shares at
the time of redemption), cash or any other form of consideration deemed
appropriate by the Board of Directors. The redemption of the Rights by the Board
of Directors may be made effective at such time, on such basis and subject to
such conditions as the Board of Directors in its sole discretion may establish.
Notwithstanding anything contained in this Agreement to the contrary, the Rights
shall not be exercisable pursuant to Section 11(a)(ii) hereof prior to the
expiration or termination of the Company's right of redemption under this
Section 23(b)(i).

            (ii) In addition, the Board of Directors of the Company may, at its
option, at any time after the time a Person becomes an Acquiring Person and the
expiration of any period during which the holder of Rights may exercise the
rights under Section 11(a)(ii) hereof but prior to any event described in clause
(x), (y) or (z) of the first sentence of Section 13 hereof, redeem all but not
less than all of the then outstanding Rights at the Redemption Price (x) in
connection with any merger, consolidation or sale or other transfer (in one
transaction or in a series of related transactions) of assets or earning power
aggregating 50% or more of the assets or earning power of the Company and its
subsidiaries (taken as a whole) in which all holders of Common Shares are
treated alike and not involving (other than as a holder of Common Shares being
treated like all other such holders) an Interested Stockholder or a Transaction
Person or (y)(A) if


                                      27.
<PAGE>   31
and for so long as the Acquiring Person is not thereafter the Beneficial Owner
of 15% or more of the then outstanding Common Shares, and (B) at the time of
redemption no other Persons are Acquiring Persons.

      (c) Immediately upon the action of the Board of Directors of the Company
ordering the redemption of the Rights pursuant to Section 23(b) hereof, and
without any further action and without any notice, the right to exercise the
Rights will terminate and the only right thereafter of the holders of Rights
shall be to receive the Redemption Price. The Company shall promptly give public
notice of any such redemption; provided, however, that the failure to give, or
any defect in, any such notice shall not affect the validity of such redemption.
Within 10 days after such action of the Board of Directors ordering the
redemption of the Rights pursuant to Section 23(b) hereof, the Company shall
mail a notice of redemption to all the holders of the then outstanding Rights at
their last addresses as they appear upon the registry books of the Rights Agent
or, prior to the Distribution Date, on the registry books of the transfer agent
for the Common Shares, provided, however, that failure to give, or any defect
in, any such notice shall not affect the validity of such redemption. Any notice
which is mailed in the manner herein provided shall be deemed given, whether or
not the holder receives the notice. Each such notice of redemption will state
the method by which the payment of the Redemption Price will be made. Neither
the Company nor any of its Affiliates or Associates may redeem, acquire or
purchase for value any Rights at any time in any manner other than that
specifically set forth in this Section 23 or in Section 24 hereof, and other
than in connection with the purchase of Common Shares prior to the Distribution
Date.

      (d) The Company may, at its option, discharge all of its obligations with
respect to any redemption of the Rights by (i) issuing a press release
announcing the manner of redemption of the Rights and (ii) mailing payment of
the Redemption Price to the registered holders of the Rights at their last
addresses as they appear on the registry books of the Rights Agent or, prior to
the Distribution Date, on the registry books of the transfer agent for the
Common Shares, and upon such action, all outstanding Right Certificates shall be
null and void without any further action by the Company.

SECTION 24. EXCHANGE.

      (a) The Board of Directors of the Company may, at its option, at any time
after any Person becomes an Acquiring Person, exchange all or part of the then
outstanding and exercisable Rights (which shall not include Rights that have
become void pursuant to the provisions of Section 11(a)(ii) hereof) for Common
Shares at an exchange ratio of one Common Share per Right, appropriately
adjusted to reflect any stock split, stock dividend or similar transaction
occurring after the date hereof (such exchange ratio being hereinafter referred
to as the "Exchange Ratio"). Notwithstanding the foregoing, the Board of
Directors shall not be empowered to effect such exchange at any time after any
Person (other than the Company, any Subsidiary of the Company, any employee
benefit plan of the Company or any such Subsidiary, or any entity holding Common
Shares for or pursuant to the terms of any such plan), together with all
Affiliates and Associates of such Person, becomes the Beneficial Owner of 50% or
more of the Common Shares then outstanding.


                                      28.
<PAGE>   32
      (b) Immediately upon the action of the Board of Directors of the Company
ordering the exchange of any Rights pursuant to Section 24(a) hereof and without
any further action and without any notice, the right to exercise such Rights
shall terminate and the only right thereafter of a holder of such Rights shall
be to receive that number of Common Shares equal to the number of such Rights
held by such holder multiplied by the Exchange Ratio. The Company shall promptly
give public notice of any such exchange; provided, however, that the failure to
give, or any defect in, such notice shall not affect the validity of such
exchange. The Company promptly shall mail a notice of any such exchange to all
of the holders of such Rights at their last addresses as they appear upon the
registry books of the Rights Agent; provided, however, that the failure to give,
or any defect in, such notice shall not affect the validity of such exchange.
Any notice which is mailed in the manner herein provided shall be deemed given,
whether or not the holder receives the notice. Each such notice of exchange will
state the method by which the exchange of the Common Shares for Rights will be
effected and, in the event of any partial exchange, the number of Rights which
will be exchanged. Any partial exchange shall be effected pro rata based on the
number of Rights (other than Rights which have become void pursuant to the
provisions of Section 11(a)(ii) hereof) held by each holder of Rights.

      (c) In lieu of issuing Common Shares in accordance with Section 24(a)
hereof, the Company may, if a majority of the Board of Directors then in office
determines that such action is necessary or appropriate and not contrary to the
interests of the holders of Rights, elect to (and, in the event that there are
not sufficient treasury shares and authorized but unissued Common Shares to
permit any exchange of the Rights in accordance with Section 24(a) hereof, the
Company shall) take all such action as may be necessary to authorize, issue or
pay, upon the exchange of the Rights, cash (including by way of a reduction of
the Purchase Price), property, Common Shares, other securities or any
combination thereof having an aggregate value equal to the value of the Common
Shares which otherwise would have been issuable pursuant to Section 24(a)
hereof, which aggregate value shall be determined by a nationally recognized
investment banking firm selected by a majority of the Board of Directors then in
office. For purposes of the preceding sentence, the value of the Common Shares
shall be determined pursuant to Section 11(d) hereof. Any election pursuant to
this Section 24(c) by the Board of Directors must be made within 60 days
following the date on which the event described in Section 11(a)(ii) hereof
shall have occurred. Following the occurrence on the event described in Section
11(a)(ii) hereof, a majority of the Board of Directors then in office may
suspend the exercisability of the Rights for a period of up to 60 days following
the date on which the event described in Section 11(a)(ii) hereof shall have
occurred to the extent that such directors have not determined whether to
exercise their rights of election under this Section 24(c). In the event of any
such suspension, the Company shall issue a public announcement stating that the
exercisability of the Rights has been temporarily suspended.

      (d) The Company shall not be required to issue fractions of Common Shares
or to distribute certificates which evidence fractional Common Shares. In lieu
of such fractional Common Shares, the Company shall pay to the registered
holders of the Right Certificates with regard to which such fractional Common
Shares would otherwise be issuable an amount in cash equal to the same fraction
of the current market value of a whole Common Share. For the purposes of this
Section 24(d), the current market value of a whole Common Share shall be the
closing price of a Common Share (as determined pursuant to the second sentence
of Section


                                      29.
<PAGE>   33
11(d)(i) hereof) for the Trading Day immediately after the date of the first
public announcement by the Company that an exchange is to be effected pursuant
to this Section 24.

      (e) The Company shall not be required to issue fractions of Preferred
Shares (other than fractions which are integral multiples of one one-hundredth
of a Preferred Share) upon exchange of the Rights or to distribute certificates
which evidence fractional Preferred Shares (other than fractions which are
integral multiples of one one-hundredth of a Preferred Share). Fractions of
Preferred Shares in integral multiples of one one-hundredth of a Preferred Share
may, at the election of the Company, be evidenced by depositary receipts;
provided, however, that holders of such depositary receipts shall have all of
the designations and the powers, preferences and rights, and the qualifications,
limitations and restrictions to which they are entitled as beneficial owners of
the Preferred Shares represented by such depositary receipts. In lieu of
fractional Preferred Shares that are not integral multiples of one one-hundredth
of a Preferred Share, the Company shall pay to the registered holders of Right
Certificates at the time such Rights are exercised as herein provided an amount
in cash equal to the same fraction of the current market value of one Preferred
Share. For the purposes of this Section 24(e), the current market value of a
Preferred Share shall be one hundred (100) times the closing price of a Common
Share (as determined pursuant to the second sentence of Section 11(d)(i) hereof)
for the Trading Day immediately after the date of the first public announcement
by the Company that an exchange is to be effected pursuant to this Section 24.

SECTION 25. NOTICE OF CERTAIN EVENTS.

      (a) In case the Company shall propose (i) to pay any dividend payable in
stock of any class to the holders of its Preferred Shares or to make any other
distribution to the holders of its Preferred Shares (other than a regular
quarterly cash dividend), (ii) to offer to the holders of its Preferred Shares
rights or warrants to subscribe for or to purchase any additional Preferred
Shares or shares of stock of any class or any other securities, rights or
options, (iii) to effect any reclassification of its Preferred Shares (other
than a reclassification involving only the subdivision of outstanding Preferred
Shares), (iv) to effect any consolidation or merger into or with, or to effect
any sale or other transfer (or to permit one or more of its Subsidiaries to
effect any sale or other transfer), in one or more transactions, of 50% or more
of the assets or earning power of the Company and its Subsidiaries (taken as a
whole), to any other Person, (v) to effect the liquidation, dissolution or
winding up of the Company, or (vi) to declare or pay any dividend on the Common
Shares payable in Common Shares or to effect a subdivision, combination or
consolidation of the Common Shares (by reclassification or otherwise than by
payment of dividends in Common Shares), then, in each such case, the Company
shall give to each holder of a Right Certificate, in accordance with Section 26
hereof, a notice of such proposed action, which shall specify the record date
for the purpose of such stock dividend, or distribution of rights or warrants,
or the date on which such reclassification, consolidation, merger, sale,
transfer, liquidation, dissolution, or winding up is to take place and the date
of participation therein by the holders of the Common Shares and/or the
Preferred Shares, if any such date is to be fixed, and such notice shall be so
given in the case of any action covered by clause (i) or (ii) above at least 10
days prior to the record date for determining holders of the Preferred Shares
for purposes of such action, and in the case of any such other action, at least
10 days prior to the date of the taking of such proposed action or the date of
participation therein by the holders of the Common Shares and/or the Preferred
Shares, whichever shall be the earlier.


                                      30.
<PAGE>   34
      (b) In case the event set forth in Section 11(a)(ii) hereof shall occur,
then the Company shall as soon as practicable thereafter give to each holder of
a Right Certificate, in accordance with Section 26 hereof, a notice of the
occurrence of such event, which notice shall describe the event and the
consequences of the event to holders of Rights under Section 11(a)(ii) hereof.

SECTION 26. NOTICES. Notices or demands authorized by this Agreement to be given
or made by the Rights Agent or by the holder of any Right Certificate to or on
the Company shall be sufficiently given or made if sent by first-class mail,
postage prepaid, addressed (until another address is filed in writing with the
Rights Agent) as follows:

                  CERUS CORPORATION
                  2525 Stanwell Drive, Suite 300
                  Concord, CA 94520
                  Attention: Corporate Secretary

      Subject to the provisions of Section 21 hereof, any notice or demand
authorized by this Agreement to be given or made by the Company or by the holder
of any Right Certificate to or on the Rights Agent shall be sufficiently given
or made if sent by first-class mail, postage prepaid, addressed (until another
address is filed in writing with the Company) as follows:

                  NORWEST BANK MINNESOTA, N.A
                  161 North Concord Exchange Street
                  South St. Paul, MN 55075-0738
                  Attn: Michael G. Gaughran

      Notices or demands authorized by this Agreement to be given or made by the
Company or the Rights Agent to the holder of any Right Certificate shall be
sufficiently given or made if sent by first-class mail, postage prepaid,
addressed to such holder at the address of such holder as shown on the registry
books of the Company.

SECTION 27. SUPPLEMENTS AND AMENDMENTS. Prior to the Distribution Date, the
Company and the Rights Agent shall, if the Company so directs, supplement or
amend any provision of this Agreement without the approval of any holders of the
Rights. From and after the Distribution Date, the Company and the Rights Agent
shall, if the Company so directs, from time to time supplement or amend any
provision of this Agreement without the approval of any holders of Right
Certificates in order to (i) cure any ambiguity, (ii) correct or supplement any
provision contained herein which may be defective or inconsistent with any other
provisions herein, or (iii) change any other provisions with respect to the
Rights which the Company may deem necessary or desirable; provided, however,
that no such supplement or amendment shall be made which would adversely affect
the interests of the holders of Rights (other than the interests of an Acquiring
Person or its Affiliates or Associates). Any supplement or amendment adopted
during any period after any Person has become an Acquiring Person but prior to
the Distribution Date shall become null and void unless such supplement or
amendment could have been adopted by the Company from and after the Distribution
Date. Any such supplement or amendment shall be evidenced by a writing signed by
the Company and the Rights Agent. Upon delivery of a certificate from an
appropriate officer of the Company which states that the proposed supplement


                                      31.
<PAGE>   35
or amendment is in compliance with the terms of this Section 27, the Rights
Agent shall execute such supplement or amendment unless the Rights Agent shall
have determined in good faith that such supplement or amendment would adversely
affect its interest under this Agreement. Prior to the Distribution Date, the
interests of the holders of Rights shall be deemed coincident with the interests
of the holders of Common Shares.

SECTION 28. DETERMINATION AND ACTIONS BY THE BOARD OF DIRECTORS, ETC. For all
purposes of this Agreement, any calculation of the number of Common Shares
outstanding at any particular time, including for purposes of determining the
particular percentage of such outstanding Common Shares or any other securities
of which any Person is the Beneficial Owner, shall be made in accordance with
the last sentence of Rule 13d-3(d)(1)(i) of the General Rules and Regulations
under the Exchange Act as in effect on the date of this Agreement. The Board of
Directors of the Company shall have the exclusive power and authority to
administer this Agreement and to exercise all rights and powers specifically
granted to the Board, or the Company, or as may be necessary or advisable in the
administration of this Agreement, including without limitation, the right and
power to (i) interpret the provisions of this Agreement, and (ii) make all
determinations deemed necessary or advisable for the administration of this
Agreement (including a determination to redeem or not redeem the Rights or to
amend the Agreement). All such actions, calculations, interpretations and
determinations (including, for purposes of clause (y) below, all omissions with
respect to the foregoing) which are done or made by the Board in good faith,
shall (x) be final, conclusive and binding on the Rights Agent and the holders
of the Rights, and (y) not subject the Board to any liability to the holders of
the Rights.

SECTION 29. SUCCESSORS. All the covenants and provisions of this Agreement by or
for the benefit of the Company or the Rights Agent shall bind and inure to the
benefit of their respective successors and assigns hereunder.

SECTION 30. BENEFITS OF THIS AGREEMENT. Nothing in this Agreement shall be
construed to give to any person or corporation other than the Company, the
Rights Agent and the registered holders of the Right Certificates (and, prior to
the Distribution Date, the Common Shares) any legal or equitable right, remedy
or claim under this Agreement; but this Agreement shall be for the sole and
exclusive benefit of the Company, the Rights Agent and the registered holders of
the Right Certificates (and, prior to the Distribution Date, the Common Shares).

SECTION 31. SEVERABILITY. If any term, provision, covenant or restriction of
this Agreement is held by a court of competent jurisdiction or other authority
to be invalid, void or unenforceable, the remainder of the terms, provisions,
covenants and restrictions of this Agreement shall remain in full force and
effect and shall in no way be affected, impaired or invalidated.

SECTION 32. GOVERNING LAW. This Agreement and each Right Certificate issued
hereunder shall be deemed to be a contract made under the laws of the State of
Delaware and for all purposes shall be governed by and construed in accordance
with the laws of such State applicable to contracts to be made and performed
entirely within such State.


                                      32.
<PAGE>   36
SECTION 33. COUNTERPARTS. This Agreement may be executed in any number of
counterparts and each of such counterparts shall for all purposes be deemed to
be an original, and all such counterparts shall together constitute but one and
the same instrument.

SECTION 34. DESCRIPTIVE HEADINGS. Descriptive headings of the several Sections
of this Agreement are inserted for convenience only and shall not control or
affect the meaning or construction of any of the provisions hereof.


                                      33.
<PAGE>   37

      IN WITNESS WHEREOF, parties whereto have caused this Agreement to be duly
executed, all as of the day and year first above written.

ATTEST:                                   CERUS CORPORATION

/s/ LORI ROLL                             /s/ STEPHEN T. ISAACS
- ---------------------------------         --------------------------------------
LORI ROLL                                 STEPHEN T. ISAACS
SECRETARY                                 PRESIDENT AND CEO


ATTEST:                                   NORWEST BANK MINNESOTA, N.A.

By:    /s/ KARRI VAN DELL                 By: /s/ MIKE GAUGHRAN
       --------------------------             ----------------------------------
                                              ACCOUNTS MANAGER
Title: ASSISTANT VICE PRESIDENT
       --------------------------

<PAGE>   38
                                     FORM OF
                           CERTIFICATE OF DESIGNATION

                                       OF

                  SERIES C JUNIOR PARTICIPATING PREFERRED STOCK

                         (EXHIBIT A TO RIGHTS AGREEMENT)

                         (PURSUANT TO SECTION 151 OF THE
                        DELAWARE GENERAL CORPORATION LAW)


      CERUS CORPORATION, a corporation organized and existing under the General
Corporation Law of the State of Delaware (hereinafter called the "Company"),
hereby certifies that the following resolution was adopted by the Board of
Directors of the Corporation as required by Section 151 of the General
Corporation Law at a meeting duly called and held on November 3, 1999:

      RESOLVED, that pursuant to the authority granted to and vested in the
Board of Directors of the Company in accordance with the provisions of its
Amended and Restated Certificate of Incorporation, the Board of Directors hereby
creates a series of Preferred Stock, par value $.001 per share, of the Company
and hereby states the designation and number of shares, and fixes the relative
designations and the powers, preferences and rights, and the qualifications,
limitations and restrictions thereof (in addition to the provisions set forth in
the Certificate of Incorporation of the Company, which are applicable to the
Preferred Stock of all classes and series), as follows:

Series C Junior Participating Preferred Stock:

      SECTION 1. DESIGNATION AND AMOUNT. Two hundred fifty thousand (250,000)
            shares of Preferred Stock, $.001 par value, are designated "Series C
            Junior Participating Preferred Stock" with the designations and the
            powers, preferences and rights, and the qualifications, limitations
            and restrictions specified herein (the "Junior Preferred Stock").
            Such number of shares may be increased or decreased by resolution of
            the Board of Directors; provided, that no decrease shall reduce the
            number of shares of Junior Preferred Stock to a number less than the
            number of shares then outstanding plus the number of shares reserved
            for issuance upon the exercise of outstanding options, rights or
            warrants or upon the conversion of


                                      A-1
<PAGE>   39
            any outstanding securities issued by the Company convertible into
            Junior Preferred Stock.


                                      A-2
<PAGE>   40
      SECTION 2. DIVIDENDS AND DISTRIBUTIONS.

            (A)   Subject to the rights of the holders of any shares of any
                  series of Preferred Stock (or any similar stock) ranking prior
                  and superior to the Junior Preferred Stock with respect to
                  dividends, the holders of shares of Junior Preferred Stock, in
                  preference to the holders of Common Stock, par value $.001 per
                  share (the "Common Stock"), of the Company, and of any other
                  junior stock, shall be entitled to receive, when, as and if
                  declared by the Board of Directors out of funds legally
                  available for the purpose, quarterly dividends payable in cash
                  on the first day of April, July, October and January in each
                  year (each such date being referred to herein as a "Quarterly
                  Dividend Payment Date"), commencing on the first Quarterly
                  Dividend Payment Date after the first issuance of a share or
                  fraction of a share of Junior Preferred Stock, in an amount
                  per share (rounded to the nearest cent) equal to the greater
                  of (a) $l.00 or (b) subject to the provision for adjustment
                  hereinafter set forth, 100 times the aggregate per share
                  amount of all cash dividends, and 100 times the aggregate per
                  share amount (payable in kind) of all non-cash dividends or
                  other distributions, other than a dividend payable in shares
                  of Common Stock or a subdivision of the outstanding shares of
                  Common Stock (by reclassification or otherwise), declared on
                  the Common Stock since the immediately preceding Quarterly
                  Dividend Payment Date or, with respect to the first Quarterly
                  Dividend Payment Date, since the first issuance of any share
                  or fraction of a share of Junior Preferred Stock. In the event
                  the Company shall at any time declare or pay any dividend on
                  the Common Stock payable in shares of Common Stock, or effect
                  a subdivision or combination or consolidation of the
                  outstanding shares of Common Stock (by reclassification or
                  otherwise than by payment of a dividend in shares of Common
                  Stock) into a greater or lesser number of shares of Common
                  Stock, then in each such case the amount to which holders of
                  shares of Junior Preferred Stock were entitled immediately
                  prior to such event under clause (b) of the preceding sentence
                  shall be adjusted by multiplying such amount by a fraction,
                  the numerator of which is the number of shares of Common Stock
                  outstanding immediately after such event and the denominator
                  of which is the number of shares of Common Stock that were
                  outstanding immediately prior to such event.

            (B)   The Company shall declare a dividend or distribution on the
                  Junior Preferred Stock as provided in paragraph (A) of this
                  Section immediately after it declares a dividend or
                  distribution on the Common Stock (other than a dividend
                  payable in shares of Common Stock); provided, that in the
                  event no dividend or distribution shall have been declared on
                  the Common Stock during the period between any Quarterly
                  Dividend Payment Date


                                      A-3
<PAGE>   41
                  and the next subsequent Quarterly Dividend Payment Date, a
                  dividend of $1.00 per share on the Junior Preferred Stock
                  shall nevertheless be payable on such subsequent Quarterly
                  Dividend Payment Date.

            (C)   Dividends shall begin to accrue and be cumulative on
                  outstanding shares of Junior Preferred Stock from the
                  Quarterly Dividend Payment Date next preceding the date of
                  issue of such shares, unless the date of issue of such shares
                  is prior to the record date for the first Quarterly Dividend
                  Payment Date, in which case dividends on such shares shall
                  begin to accrue from the date of issue of such shares, or
                  unless the date of issue is a Quarterly Dividend Payment Date
                  or is a date after the record date for the determination of
                  holders of shares of Junior Preferred Stock entitled to
                  receive a quarterly dividend and before such Quarterly
                  Dividend Payment Date, in either of which events such
                  dividends shall begin to accrue and be cumulative from such
                  Quarterly Dividend Payment Date. Accrued but unpaid dividends
                  shall not bear interest. Dividends paid on the shares of
                  Junior Preferred Stock in an amount less than the total amount
                  of such dividends at the time accrued and payable on such
                  shares shall be allocated pro rata on a share-by-share basis
                  among all such shares at the time outstanding. The Board of
                  Directors may fix a record date for the determination of
                  holders of shares of Junior Preferred Stock entitled to
                  receive payment of a dividend or distribution declared
                  thereon, which record date shall be not more than 60 days
                  prior to the date fixed for the payment thereof.

      SECTION 3. VOTING RIGHTS. The holders of shares of Junior Preferred Stock
            shall have the following voting rights:

            (A)   Subject to the provision for adjustment hereinafter set forth,
                  each share of Junior Preferred Stock shall entitle the holder
                  thereof to 100 votes on all matters submitted to a vote of the
                  stockholders of the Company. In the event the Company shall at
                  any time declare or pay any dividend on the Common Stock
                  payable in shares of Common Stock, or effect a subdivision or
                  combination or consolidation of the outstanding shares of
                  Common Stock (by reclassification or otherwise than by payment
                  of a dividend in shares of Common Stock) into a greater or
                  lesser number of shares of Common Stock, then in each such
                  case the number of votes per share to which holders of shares
                  of Junior Preferred Stock were entitled immediately prior to
                  such event shall be adjusted by multiplying such number by a
                  fraction, the numerator of which is the number of shares of
                  Common Stock outstanding immediately after such event and the
                  denominator of which is the number of shares of Common Stock
                  that were outstanding immediately prior to such event.


                                      A-4
<PAGE>   42
            (B)   Except as otherwise provided herein, in any other Certificate
                  of Designation creating a series of Preferred Stock or any
                  similar stock, or by law, the holders of shares of Junior
                  Preferred Stock and the holders of shares of Common Stock and
                  any other capital stock of the Company having general voting
                  rights shall vote together as one class on all matters
                  submitted to a vote of stockholders of the Company.

            (C)   Except as set forth herein, or as otherwise provided by law,
                  holders of Junior Preferred Stock shall have no special voting
                  rights and their consent shall not be required (except to the
                  extent they are entitled to vote with holders of Common Stock
                  as set forth herein) for taking any corporate action.

      SECTION 4. CERTAIN RESTRICTIONS.

            (A)   Whenever quarterly dividends or other dividends or
                  distributions payable on the Junior Preferred Stock as
                  provided in Section 2 are in arrears, thereafter and until all
                  accrued and unpaid dividends and distributions, whether or not
                  declared, on shares of Junior Preferred Stock outstanding
                  shall have been paid in full, the Company shall not:

                  (i)   declare or pay dividends, or make any other
                        distributions, on any shares of stock ranking junior
                        (either as to dividends or upon liquidation, dissolution
                        or winding up) to the Junior Preferred Stock;

                  (ii)  declare or pay dividends, or make any other
                        distributions, on any shares of stock ranking on a
                        parity (either as to dividends or upon liquidation,
                        dissolution or winding up) with the Junior Preferred
                        Stock, except dividends paid ratably on the Junior
                        Preferred Stock and all such parity stock on which
                        dividends are payable or in arrears in proportion to the
                        total amounts to which the holders of all such shares
                        are then entitled;

                  (iii) redeem or purchase or otherwise acquire for
                        consideration shares of any stock ranking junior (either
                        as to dividends or upon liquidation, dissolution or
                        winding up) to the Junior Preferred Stock, provided that
                        the Company may at any time redeem, purchase or
                        otherwise acquire shares of any such junior stock in
                        exchange for shares of any stock of the Company ranking
                        junior (either as to dividends or upon dissolution,
                        liquidation or winding up) to the Junior Preferred
                        Stock; or


                                      A-5
<PAGE>   43
                  (iv)  redeem or purchase or otherwise acquire for
                        consideration any shares of Junior Preferred Stock, or
                        any shares of stock ranking on a parity (either as to
                        dividends or upon liquidation, dissolution or winding
                        up) with the Junior Preferred Stock, except in
                        accordance with a purchase offer made in writing or by
                        publication (as determined by the Board of Directors) to
                        all holders of such shares upon such terms as the Board
                        of Directors, after consideration of the respective
                        annual dividend rates and other relative rights and
                        preferences of the respective series and classes, shall
                        determine in good faith will result in fair and
                        equitable treatment among the respective series or
                        classes.

            (B)   The Company shall not permit any subsidiary of the Company to
                  purchase or otherwise acquire for consideration any shares of
                  stock of the Company unless the Company could, under paragraph
                  (A) of this Section 4, purchase or otherwise acquire such
                  shares at such time and in such manner.

      SECTION 5. REACQUIRED SHARES. Any shares of Junior Preferred Stock
            purchased or otherwise acquired by the Company in any manner
            whatsoever shall be retired and cancelled promptly after the
            acquisition thereof. All such shares shall upon their cancellation
            become authorized but unissued shares of Preferred Stock and may be
            reissued as part of a new series of Preferred Stock subject to the
            conditions and restrictions on issuance set forth herein, in the
            Amended and Restated Certificate of Incorporation, or in any other
            Certificate of Designation creating a series of Preferred Stock or
            any similar stock or as otherwise required by law.

      SECTION 6. LIQUIDATION, DISSOLUTION OR WINDING UP. Upon any liquidation,
            dissolution or winding up of the Company, no distribution shall be
            made (1) to the holders of shares of stock ranking junior (either as
            to dividends or upon liquidation, dissolution or winding up) to the
            Junior Preferred Stock unless, prior thereto, the holders of shares
            of Junior Preferred Stock shall have received $100 per share, plus
            an amount equal to accrued and unpaid dividends and distributions
            thereon, whether or not declared, to the date of such payment,
            provided that the holders of shares of Junior Preferred Stock shall
            be entitled to receive an aggregate amount per share, subject to the
            provision for adjustment hereinafter set forth, equal to 100 times
            the aggregate amount to be distributed per share to holders of
            shares of Common Stock, or (2) to the holders of shares of stock
            ranking on a parity (either as to dividends or upon liquidation,
            dissolution or winding up) with the Junior Preferred Stock, except
            distributions made ratably on the Junior Preferred Stock and all
            such parity stock in proportion to the total amounts to which the
            holders of all such shares are entitled upon such liquidation,


                                      A-6
<PAGE>   44
            dissolution or winding up. In the event the Company shall at any
            time declare or pay any dividend on the Common Stock payable in
            shares of Common Stock, or effect a subdivision or combination or
            consolidation of the outstanding shares of Common Stock (by
            reclassification or otherwise than by payment of a dividend in
            shares of Common Stock) into a greater or lesser number of shares of
            Common Stock, then in each such case the aggregate amount to which
            holders of shares of Junior Preferred Stock were entitled
            immediately prior to such event under the proviso in clause (1) of
            the preceding sentence shall be adjusted by multiplying such amount
            by a fraction the numerator of which is the number of shares of
            Common Stock outstanding immediately after such event and the
            denominator of which is the number of shares of Common Stock that
            were outstanding immediately prior to such event.

      SECTION 7. CONSOLIDATION, MERGER, ETC. In case the Company shall enter
            into any consolidation, merger, combination or other transaction in
            which the shares of Common Stock are exchanged for or changed into
            other stock or securities, cash and/or any other property, then in
            any such case each share of Junior Preferred Stock shall at the same
            time be similarly exchanged or changed into an amount per share,
            subject to the provision for adjustment hereinafter set forth, equal
            to 100 times the aggregate amount of stock, securities, cash and/or
            any other property (payable in kind), as the case may be, into which
            or for which each share of Common Stock is changed or exchanged. In
            the event the Company shall at any time declare or pay any dividend
            on the Common Stock payable in shares of Common Stock, or effect a
            subdivision or combination or consolidation of the outstanding
            shares of Common Stock (by reclassification or otherwise than by
            payment of a dividend in shares of Common Stock) into a greater or
            lesser number of shares of Common Stock, then in each such case the
            amount set forth in the preceding sentence with respect to the
            exchange or change of shares of Junior Preferred Stock shall be
            adjusted by multiplying such amount by a fraction, the numerator of
            which is the number of shares of Common Stock outstanding
            immediately after such event and the denominator of which is the
            number of shares of Common Stock that were outstanding immediately
            prior to such event.

      SECTION 8. NO REDEMPTION. The shares of Junior Preferred Stock shall not
            be redeemable.

      SECTION 9. RANK. The Junior Preferred Stock shall rank, with respect to
            the payment of dividends and the distribution of assets, junior to
            all series of any other class of the Company's Preferred Stock
            (including the Company's Series A Preferred Stock notwithstanding
            any provisions of the Certificate of Designation of Series A
            Preferred Stock of the Company to the contrary).


                                      A-7
<PAGE>   45
      SECTION 10. AMENDMENT. The Amended and Restated Certificate of
            Incorporation of the Company shall not be amended in any manner
            which would materially alter or change the powers, preferences or
            special rights of the Junior Preferred Stock so as to affect them
            adversely without the affirmative vote of the holders of at least
            two-thirds of the outstanding shares of Junior Preferred Stock,
            voting together as a single class.


                                      A-8
<PAGE>   46
      IN WITNESS WHEREOF, the undersigned have executed this certificate as of
November __, 1999.

                                       -----------------------------------------
                                       STEPHEN T. ISAACS
                                       PRESIDENT AND CEO


                                       -----------------------------------------
                                       LORI ROLL
                                       SECRETARY


                                      A-9
<PAGE>   47
                            FORM OF RIGHT CERTIFICATE
                         (EXHIBIT B TO RIGHTS AGREEMENT)

CERTIFICATE NO. R-                                                  _____ RIGHTS

      NOT EXERCISABLE AFTER NOVEMBER 3, 2009 OR EARLIER IF REDEMPTION OR
      EXCHANGE OCCURS. THE RIGHTS ARE SUBJECT TO REDEMPTION AT $.001 PER RIGHT
      AND TO EXCHANGE ON THE TERMS SET FORTH IN THE RIGHTS AGREEMENT.

                                RIGHT CERTIFICATE

                                CERUS CORPORATION

This certifies that ___________________ or registered assigns, is the registered
owner of the number of Rights set forth above, each of which entitles the owner
thereof, subject to the terms, provisions and conditions of the Rights
Agreement, dated as of November 3, 1999 (the "Rights Agreement"), between CERUS
CORPORATION, a Delaware corporation (the "Company"), and NORWEST BANK MINNESOTA,
N.A. (the "Rights Agent"), to purchase from the Company at any time after the
Distribution Date (as such term is defined in the Rights Agreement) and prior to
5:00 p.m., Pacific Time, on November 3, 2009 at the office of the Rights Agent
designated for such purpose, or at the office of its successor as Rights Agent,
one one-hundredth of a fully paid non-assessable share of Series C Junior
Participating Preferred Stock, par value $.001 per share (the "Preferred
Shares"), of the Company, at a purchase price of $170 per one one-hundredth of a
Preferred Share (the "Purchase Price"), upon presentation and surrender of this
Right Certificate with the Form of Election to Purchase duly executed. The
number of Rights evidenced by this Right Certificate (and the number of one
one-hundredths of a Preferred Share which may be purchased upon exercise hereof)
set forth above, and the Purchase Price set forth above, are the number and
Purchase Price as of November 3, 1999, based on the Preferred Shares as
constituted at such date.

From and after the time any Person becomes an Acquiring Person, (as such terms
are defined in the Rights Agreement), if the Rights evidenced by this Right
Certificate are beneficially owned by (i) an Acquiring Person or an Affiliate or
Associate of any such Acquiring Person (as such terms are defined in the Rights
Agreement), (ii) a transferee of any such Acquiring Person, Associate or
Affiliate who becomes a transferee after the Acquiring Person becomes such, or
(iii) under certain circumstances specified in the Rights Agreement, a
transferee of any such Acquiring Person, Associate or Affiliate who becomes a
transferee prior to or concurrently with the Acquiring Person becoming such,
such Rights shall become null and void without any further


                                      B-1
<PAGE>   48
action and no holder hereof shall have any right with respect to such Rights
from and after the time any Person becomes an Acquiring Person.

As provided in the Rights Agreement, the Purchase Price and the number of one
one-hundredths of a Preferred Share which may be purchased upon the exercise of
the Rights evidenced by this Right Certificate are subject to modification and
adjustment upon the happening of certain events.

This Right Certificate is subject to all of the terms, provisions and conditions
of the Rights Agreement, as amended from time to time, which terms, provisions
and conditions are hereby incorporated herein by reference and made a part
hereof and to which Rights Agreement reference is hereby made for a full
description of the rights, limitations of rights, obligations, duties and
immunities hereunder of the Rights Agent, the Company and the holders of the
Right Certificates. Copies of the Rights Agreement are on file at the principal
executive offices of the Company and the above-mentioned offices of the Rights
Agent.

This Right Certificate, with or without other Right Certificates, upon surrender
at the office of the Rights Agent designated for such purpose, may be exchanged
for another Right Certificate or Right Certificates of like tenor and date
evidencing Rights entitling the holder to purchase a like aggregate number of
Preferred Shares as the Rights evidenced by the Right Certificate or Right
Certificates surrendered shall have entitled such holder to purchase. If this
Right Certificate shall be exercised in part, the holder shall be entitled to
receive upon surrender hereof another Right Certificate or Right Certificates
for the number of whole Rights not exercised.

Subject to the provisions of the Rights Agreement, the Rights evidenced by this
Certificate (i) may be redeemed by the Company at a redemption price of $.001
per Right or (ii) may be exchanged in whole or in part for shares of the
Company's Common Stock, par value $.001 per share, or, upon circumstances set
forth in the Rights Agreement, cash, property or other securities of the
Company, including fractions of a share of Preferred Stock.

No fractional Preferred Shares will be issued upon the exercise of any Right or
Rights evidenced hereby (other than fractions which are integral multiples of
one one-hundredth of a Preferred Share, which may, at the election of the
Company, be evidenced by depositary receipts) but in lieu thereof a cash payment
will be made, as provided in the Rights Agreement.

No holder of this Right Certificate shall be entitled to vote or receive
dividends or be deemed for any purpose the holder of the Preferred Shares or of
any other securities of the Company which may at any time be issuable on the
exercise hereof, nor shall anything contained in the Rights Agreement or herein
be construed to confer upon the holder hereof, as such, any of the rights of a
stockholder of the Company or any right to vote for the election of directors or
upon any matter submitted to stockholders at any meeting thereof, or to give or
withhold consent to any corporate action, or to receive notice of meetings or
other actions affecting stockholders (except as provided in the Rights
Agreement), or to receive dividends or subscription rights, or otherwise,


                                      B-2
<PAGE>   49
until the Right or Rights evidenced by this Right Certificate shall have been
exercised as provided in the Rights Agreement.

This Right Certificate shall not be valid or obligatory for any purpose until it
shall have been countersigned by the Rights Agent.

WITNESS the facsimile signature of the proper officers of the Company and its
corporate seal. Dated as of __________.

ATTEST:                                   CERUS CORPORATION


- ----------------------------------        --------------------------------------
[SIGNING COMPANY SECRETARY'S NAME]        [SIGNING COMPANY SECRETARY'S NAME]
[TITLE]                                   [TITLE]


COUNTERSIGNED:

NORWEST BANK MINNESOTA, N.A.
as Rights Agent

By:
   ------------------------------
   [AUTHORIZED SIGNATURE]


                                      B-3
<PAGE>   50
                               FORM OF ASSIGNMENT

                (TO BE EXECUTED BY THE REGISTERED HOLDER IF SUCH
               HOLDER DESIRES TO TRANSFER THE RIGHT CERTIFICATE.)

FOR  VALUE  RECEIVED   ______________________________________   hereby  sells,
assigns and transfers unto

________________________________________________________________________________
                  (Please print name and address of transferee)

______________________________________________________________ this Right
Certificate, together with all right, title and interest therein, and does
hereby irrevocably constitute and appoint ________________________ Attorney, to
transfer the within Right Certificate on the books of the within-named Company,
with full power of substitution.

Dated: ____________________

                                          ______________________________________
                                          Signature


                                      B-4
<PAGE>   51
SIGNATURE MEDALLION GUARANTEED:

Signatures must be medallion guaranteed by an "eligible guarantor institution"
as defined in Rule 17Ad-15 promulgated under the Securities Exchange Act of
1934, as amended.

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

The undersigned hereby certifies that (1) the Rights evidenced by this Right
Certificate are not being sold, assigned or transferred by or on behalf of a
Person who is or was an Acquiring Person, an Interested Stockholder or an
Affiliate or Associate thereof (as such terms are defined in the Rights
Agreement); and (2) after due inquiry and to the best of the knowledge of the
undersigned, the undersigned did not acquire the Rights evidenced by this Right
Certificate from any Person who is or was an Acquiring Person, an Interested
Stockholder, or an Affiliate or Associate thereof.


                                          --------------------------------------
                                          Signature


                                      B-5
<PAGE>   52
                         FORM OF ELECTION TO PURCHASE

                  (TO BE EXECUTED IF HOLDER DESIRES TO EXERCISE
                  RIGHTS REPRESENTED BY THE RIGHT CERTIFICATE.)

To Norwest Bank Minnesota, N.A.:

The undersigned hereby irrevocably elects to exercise __________________ Rights
represented by this Right Certificate to purchase the Preferred Shares issuable
upon the exercise of such Rights and requests that certificates for such
Preferred Shares be issued in the name of:

Please insert social security
or other identifying number: ______________

________________________________________________________________________________
                       (Please print name and address)

________________________________________________________________________________


If such number of Rights shall not be all the Rights evidenced by this Right
Certificate, a new Right Certificate for the balance remaining of such Rights
shall be registered in the name of and delivered to:

Please insert social security
or other identifying number: ______________

________________________________________________________________________________
                       (Please print name and address)

________________________________________________________________________________

Dated: _________________

                                          ______________________________________
                                          Signature


             FORM OF REVERSE SIDE OF RIGHT CERTIFICATE -- CONTINUED

                                      B-6
<PAGE>   53

SIGNATURE MEDALLION GUARANTEED:


Signatures must be medallion guaranteed by an "eligible guarantor institution"
as defined in Rule 17Ad-15 promulgated under the Securities Exchange Act of
1934, as amended.

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

The undersigned hereby certifies that (1) the Rights evidenced by this Right
Certificate are not beneficially owned by nor are they being exercised on behalf
of an Acquiring Person, an Interested Stockholder or an Affiliate or Associate
thereof (as such terms are defined in the Rights Agreement); and (2) after due
inquiry and to the best of the knowledge of the undersigned, the undersigned did
not acquire the Rights evidenced by this Right Certificate from any Person who
is or was an Acquiring Person, an Interested Stockholder, or an Affiliate or
Associate thereof.


                                          --------------------------------------
                                          Signature


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

                                    NOTICE

The signature in the Form of Assignment or Form of Election to Purchase, as the
case may be, must conform to the name as written upon the face of this Right
Certificate in every particular, without alteration or enlargement or any change
whatsoever.

In the event the certification set forth above in the Form of Assignment or the
Form of Election to Purchase, as the case may be, is not completed, the Company
and the Rights Agent will deem the beneficial owner of the Rights evidenced by
this Right Certificate to be an Acquiring Person or an Affiliate or Associate
thereof (as defined in the Rights Agreement) and such Assignment or Election to
Purchase will not be honored.


                                      B-7
<PAGE>   54
                                CERUS CORPORATION

                          SUMMARY OF RIGHTS TO PURCHASE
                                PREFERRED SHARES

                           (EXHIBIT C TO RIGHTS PLAN)

On November 3, 1999, the Board of Directors of CERUS CORPORATION (the "Company")
declared a dividend of one preferred share purchase right (a "Right") for each
outstanding share of common stock, par value $.001 per share (the "Common
Shares"), of the Company. The dividend is effective as of November 23, 1999 (the
"Record Date") with respect to the stockholders of record on that date. The
Rights will also attach to new Common Shares issued after the Record Date. Each
Right entitles the registered holder to purchase from the Company one
one-hundredth of a share of Series C Junior Participating Preferred Stock, par
value $.001 per share (the "Preferred Shares"), of the Company at a price of
$170 per one one-hundredth of a Preferred Share (the "Purchase Price"), subject
to adjustment. Each Preferred Share is designed to be the economic equivalent of
100 Common Shares. The description and terms of the Rights are set forth in a
Rights Agreement dated as of November 3, 1999 (the "Rights Agreement"), between
the Company Norwest Bank Minnesota, N.A. (the "Rights Agent").

DETACHMENT AND TRANSFER OF RIGHTS

Initially, the Rights will be evidenced by the stock certificates representing
Common Shares then outstanding, and no separate Right Certificates will be
distributed. Until the earlier to occur of (i) a public announcement that a
person or group of affiliated or associated persons, has become an "Acquiring
Person" (as such term is defined in the Rights Agreement) or (ii) 10 business
days (or such later date as the Board may determine) following the commencement
of, or announcement of an intention to make, a tender offer or exchange offer
which would result in the beneficial ownership by an Acquiring Person of 15% or
more of the outstanding Common Shares (the earlier of such dates being called
the "Distribution Date"), the Rights will be evidenced, with respect to any of
the Common Share certificates outstanding as of the Record Date, by such Common
Share certificate. In general, an "Acquiring Person" is a person, the affiliates
or associates of such person, or a group, which has acquired beneficial
ownership of 15% or more of the outstanding Common Shares; provided that certain
"Excluded Stockholders" as defined in the Rights Agreement may have greater
beneficial ownership without becoming an "Acquiring Person".

The Rights Agreement provides that, until the Distribution Date (or earlier
redemption or expiration of the Rights), the Rights will be transferable with
and only with the Common Shares. Until the Distribution Date (or earlier
redemption or expiration of the Rights), new Common Share certificates issued
after the Record Date upon transfer or new issuance of Common Shares will
contain a notation incorporating the Rights Agreement by reference. Until the
Distribution Date (or earlier redemption or expiration of the Rights) the
surrender or transfer of any certificates for Common Shares outstanding as of
the Record Date, even without such notation or a copy of this Summary of Rights
being attached thereto, will also constitute the transfer of the Rights
associated with the Common Shares represented by such certificate. As soon as


                                      C-1
<PAGE>   55
practicable following the Distribution Date, separate certificates evidencing
the Rights ("Right Certificates") will be mailed to holders of record of the
Common Shares as of the close of business on the Distribution Date and such
separate Right Certificates alone will evidence the Rights.

EXERCISABILITY OF RIGHTS

The Rights are not exercisable until the Distribution Date. The Rights will
expire on November 3, 2009 (the "Final Expiration Date"), unless the Final
Expiration Date is extended or unless the Rights are earlier redeemed or
exchanged by the Company, in each case as described below. Until a Right is
exercised, the holder thereof, as such, will have no rights as a stockholder of
the Company, including, without limitation, the right to vote or to receive
dividends.

The Purchase Price payable, and the number of Preferred Shares or other
securities or property issuable or payable, upon exercise of the Rights are
subject to adjustment from time to time to prevent dilution. The number of
outstanding Rights and the number of one one-hundredths of a Preferred Share
issuable upon exercise of each Right are also subject to adjustment in the event
of a stock split of the Common Shares or a stock dividend on the Common Shares
payable in Common Shares, or subdivisions, consolidations or combinations of the
Common Shares occurring, in any such case, prior to the Distribution Date. With
certain exceptions, no adjustment in the Purchase Price will be required until
cumulative adjustments require an adjustment of at least 1% in such Purchase
Price. No fractional Preferred Shares will be issued (other than fractions which
are integral multiples of one one-hundredth of a Preferred Share, which may, at
the election of the Company, be evidenced by depositary receipts) and in lieu
thereof, an adjustment in cash will be made based on the market price of the
Preferred Shares on the last trading day prior to the date of exercise.

TERMS OF PREFERRED SHARES

Preferred Shares purchasable upon exercise of the Rights will not be redeemable.
Each Preferred Share will be entitled to a minimum preferential quarterly
dividend payment of $l per share but will be entitled to an aggregate dividend
of 100 times the dividend declared per Common Share. In the event of
liquidation, the holders of the Preferred Shares will be entitled to a minimum
preferential liquidation payment of $100 per share but will be entitled to an
aggregate payment of 100 times the payment made per Common Share. Each Preferred
Share will have 100 votes, voting together with the Common Shares. Finally, in
the event of any merger, consolidation or other transaction in which Common
Shares are exchanged, each Preferred Share will be entitled to receive 100 times
the amount received per Common Share. These rights are protected by customary
anti-dilution provisions. Because of the nature of the Preferred Shares'
dividend, liquidation and voting rights, the value of the one one-hundredth
interest in a Preferred Share purchasable upon exercise of each Right should
approximate the value of one Common Share. The Preferred Shares would rank
junior to any other series of the Company's preferred stock.


                                      C-2
<PAGE>   56
TRIGGER OF FLIP-IN AND FLIP-OVER RIGHTS

      In the event that any person or group of affiliated or associated persons
becomes an Acquiring Person, proper provision shall be made so that each holder
of a Right, other than Rights beneficially owned by the Acquiring Person or any
affiliate or associate thereof (which will thereafter be void), will thereafter
have the right to receive upon exercise that number of Common Shares having a
market value of two times the exercise price of the Right. This right will
commence on the date of public announcement that a person has become an
Acquiring Person (or the effective date of a registration statement relating to
distribution of the rights, if later) and terminate 60 days later (subject to
adjustment in the event exercise of the rights is enjoined). At the time the
rights flip in, they no longer represent the right to purchase Preferred Shares.

In the event that the Company is acquired in a merger or other business
combination transaction or 50% or more of its consolidated assets or earning
power are sold to an Acquiring Person, its affiliates or associates or certain
other persons in which such persons have an interest, proper provision will be
made so that each such holder of a Right will thereafter have the right to
receive, upon the exercise thereof at the then current exercise price of the
Right, that number of shares of common stock of the acquiring company which at
the time of such transaction will have a market value of two times the exercise
price of the Right.

REDEMPTION AND EXCHANGE OF RIGHTS

At any time prior to the earliest of (i) the close of business on the day of the
first public announcement that a person has become an Acquiring Person, or (ii)
the Final Expiration Date, the Board of Directors of the Company may redeem the
Rights in whole, but not in part, at a price of $.001 per Right (the "Redemption
Price"). In general, the redemption of the Rights may be made effective at such
time, on such basis and with such conditions as the Board of Directors in its
sole discretion may establish. Immediately upon any redemption of the Rights,
the right to exercise the Rights will terminate and the only right of the
holders of Rights will be to receive the Redemption Price.

At any time after any Person becomes an Acquiring Person and prior to the
acquisition by such person or group of 50% or more of the outstanding Common
Shares, the Board of Directors of the Company may exchange the Rights (other
than Rights owned by such person or group which will have become void), in whole
or in part, at an exchange ratio of one Common Share, or, under circumstances
set forth in the Rights Agreement, cash, property or other securities of the
Company, including fractions of a Preferred Share (or of a share of a class or
series of the Company's preferred stock having equivalent designations and the
powers, preferences and rights, and the qualifications, limitations and
restrictions), per Right (with value equal to such Common Shares).

AMENDMENT OF RIGHTS

The terms of the Rights generally may be amended by the Board of Directors of
the Company without the consent of the holders of the Rights, except that from
and after such time as the


                                      C-3
<PAGE>   57
Rights are distributed no such amendment may adversely affect the interests of
the holders of the Rights (excluding the interest of any Acquiring Person).

ADDITIONAL INFORMATION

A copy of the Rights Agreement has been filed with the Securities and Exchange
Commission as an Exhibit to a Current Report on Form 8-K dated ___________,
____. A copy of the Rights Agreement is available from the Company by writing
to: Cerus Corporation, 2525 Stanwell Drive, Suite 300, Concord, CA 94520,
Attention: Corporate Secretary. This summary description of the Rights is not
intended to be complete and is qualified in its entirety by reference to the
Rights Agreement, which is hereby incorporated herein by reference.


                                      C-4

<PAGE>   1
                                                                    EXHIBIT 99.3

CERTIFICATE NO. R-                                                  _____ RIGHTS

        NOT EXERCISABLE AFTER NOVEMBER 3, 2009 OR EARLIER IF REDEMPTION OR
        EXCHANGE OCCURS. THE RIGHTS ARE SUBJECT TO REDEMPTION AT $.001 PER RIGHT
        AND TO EXCHANGE ON THE TERMS SET FORTH IN THE RIGHTS AGREEMENT.

                                RIGHT CERTIFICATE

                                CERUS CORPORATION

        This certifies that ___________________ or registered assigns, is the
registered owner of the number of Rights set forth above, each of which entitles
the owner thereof, subject to the terms, provisions and conditions of the Rights
Agreement, dated as of November 3, 1999 (the "Rights Agreement"), between CERUS
CORPORATION, a Delaware corporation (the "Company"), and NORWEST BANK MINNESOTA,
N.A. (the "Rights Agent"), to purchase from the Company at any time after the
Distribution Date (as such term is defined in the Rights Agreement) and prior to
5:00 p.m., Pacific Time, on November 3, 2009 at the office of the Rights Agent
designated for such purpose, or at the office of its successor as Rights Agent,
one one-hundredth of a fully paid non-assessable share of Series C Junior
Participating Preferred Stock, par value $.001 per share (the "Preferred
Shares"), of the Company, at a purchase price of $170 per one one-hundredth of a
Preferred Share (the "Purchase Price"), upon presentation and surrender of this
Right Certificate with the Form of Election to Purchase duly executed. The
number of Rights evidenced by this Right Certificate (and the number of one
one-hundredths of a Preferred Share which may be purchased upon exercise hereof)
set forth above, and the Purchase Price set forth above, are the number and
Purchase Price as of November 3, 1999, based on the Preferred Shares as
constituted at such date.

        From and after the time any Person becomes an Acquiring Person, (as such
terms are defined in the Rights Agreement), if the Rights evidenced by this
Right Certificate are beneficially owned by (i) an Acquiring Person or an
Affiliate or Associate of any such Acquiring Person (as such terms are defined
in the Rights Agreement), (ii) a transferee of any such Acquiring Person,
Associate or Affiliate who becomes a transferee after the Acquiring Person
becomes such, or (iii) under certain circumstances specified in the Rights
Agreement, a transferee of any such Acquiring Person, Associate or Affiliate who
becomes a transferee prior to or concurrently with the Acquiring Person becoming
such, such Rights shall become null and void without any further action and no
holder hereof shall have any right with respect to such Rights from and after
the time any Person becomes an Acquiring Person.

        As provided in the Rights Agreement, the Purchase Price and the number
of one one-hundredths of a Preferred Share which may be purchased upon the
exercise of the Rights


                                       1
<PAGE>   2
evidenced by this Right Certificate are subject to modification and adjustment
upon the happening of certain events.

        This Right Certificate is subject to all of the terms, provisions and
conditions of the Rights Agreement, as amended from time to time, which terms,
provisions and conditions are hereby incorporated herein by reference and made a
part hereof and to which Rights Agreement reference is hereby made for a full
description of the rights, limitations of rights, obligations, duties and
immunities hereunder of the Rights Agent, the Company and the holders of the
Right Certificates. Copies of the Rights Agreement are on file at the principal
executive offices of the Company and the above-mentioned offices of the Rights
Agent.

        This Right Certificate, with or without other Right Certificates, upon
surrender at the office of the Rights Agent designated for such purpose, may be
exchanged for another Right Certificate or Right Certificates of like tenor and
date evidencing Rights entitling the holder to purchase a like aggregate number
of Preferred Shares as the Rights evidenced by the Right Certificate or Right
Certificates surrendered shall have entitled such holder to purchase. If this
Right Certificate shall be exercised in part, the holder shall be entitled to
receive upon surrender hereof another Right Certificate or Right Certificates
for the number of whole Rights not exercised.

        Subject to the provisions of the Rights Agreement, the Rights evidenced
by this Certificate (i) may be redeemed by the Company at a redemption price of
$.001 per Right or (ii) may be exchanged in whole or in part for shares of the
Company's Common Stock, par value $.001 per share, or, upon circumstances set
forth in the Rights Agreement, cash, property or other securities of the
Company, including fractions of a share of Preferred Stock.

        No fractional Preferred Shares will be issued upon the exercise of any
Right or Rights evidenced hereby (other than fractions which are integral
multiples of one one-hundredth of a Preferred Share, which may, at the election
of the Company, be evidenced by depositary receipts) but in lieu thereof a cash
payment will be made, as provided in the Rights Agreement.

        No holder of this Right Certificate shall be entitled to vote or receive
dividends or be deemed for any purpose the holder of the Preferred Shares or of
any other securities of the Company which may at any time be issuable on the
exercise hereof, nor shall anything contained in the Rights Agreement or herein
be construed to confer upon the holder hereof, as such, any of the rights of a
stockholder of the Company or any right to vote for the election of directors or
upon any matter submitted to stockholders at any meeting thereof, or to give or
withhold consent to any corporate action, or to receive notice of meetings or
other actions affecting stockholders (except as provided in the Rights
Agreement), or to receive dividends or subscription rights, or otherwise, until
the Right or Rights evidenced by this Right Certificate shall have been
exercised as provided in the Rights Agreement.

        This Right Certificate shall not be valid or obligatory for any purpose
until it shall have been countersigned by the Rights Agent.

                                       2
<PAGE>   3
        WITNESS the facsimile signature of the proper officers of the Company
and its corporate seal. Dated as of __________.

ATTEST:                                     CERUS CORPORATION

___________________________________         ____________________________________
[SIGNING COMPANY SECRETARY'S NAME]          [SIGNING COMPANY SECRETARY'S NAME]
[TITLE]                                     [TITLE]

COUNTERSIGNED:

NORWEST BANK MINNESOTA, N.A.

as Rights Agent

By:________________________________
[AUTHORIZED SIGNATURE]


                                       3
<PAGE>   4
                    FORM OF REVERSE SIDE OF RIGHT CERTIFICATE

                               FORM OF ASSIGNMENT

                (TO BE EXECUTED BY THE REGISTERED HOLDER IF SUCH
               HOLDER DESIRES TO TRANSFER THE RIGHT CERTIFICATE.)

        FOR VALUE RECEIVED ______________________________________ hereby sells,
assigns and transfers unto

________________________________________________________________________________
                  (Please print name and address of transferee)

______________________________________________________________ this Right
Certificate, together with all right, title and interest therein, and does
hereby irrevocably constitute and appoint ________________________ Attorney, to
transfer the within Right Certificate on the books of the within-named Company,
with full power of substitution.

Dated:____________________

                                            ____________________________________
                                            Signature


             FORM OF REVERSE SIDE OF RIGHT CERTIFICATE -- CONTINUED

                                       4
<PAGE>   5
SIGNATURE MEDALLION GUARANTEED:

        Signatures must be medallion guaranteed by an "eligible guarantor
institution" as defined in Rule 17Ad-15 promulgated under the Securities
Exchange Act of 1934, as amended.

            _______________________________________________________

        The undersigned hereby certifies that (1) the Rights evidenced by this
Right Certificate are not being sold, assigned or transferred by or on behalf of
a Person who is or was an Acquiring Person, an Interested Stockholder or an
Affiliate or Associate thereof (as such terms are defined in the Rights
Agreement); and (2) after due inquiry and to the best of the knowledge of the
undersigned, the undersigned did not acquire the Rights evidenced by this Right
Certificate from any Person who is or was an Acquiring Person, an Interested
Stockholder, or an Affiliate or Associate thereof.


                                             ___________________________________
                                             Signature


                                       5
<PAGE>   6
                          FORM OF ELECTION TO PURCHASE

                  (TO BE EXECUTED IF HOLDER DESIRES TO EXERCISE
                  RIGHTS REPRESENTED BY THE RIGHT CERTIFICATE.)

To Norwest Bank Minnesota, N.A.:

        The undersigned hereby irrevocably elects to exercise __________________
Rights represented by this Right Certificate to purchase the Preferred Shares
issuable upon the exercise of such Rights and requests that certificates for
such Preferred Shares be issued in the name of:

Please insert social security
or other identifying number:______________


________________________________________________________________________________
                         (Please print name and address)

________________________________________________________________________________

If such number of Rights shall not be all the Rights evidenced by this Right
Certificate, a new Right Certificate for the balance remaining of such Rights
shall be registered in the name of and delivered to:

Please insert social security
or other identifying number:______________


________________________________________________________________________________
                         (Please print name and address)

________________________________________________________________________________

Dated:_________________

                                              __________________________________
                                              Signature


             FORM OF REVERSE SIDE OF RIGHT CERTIFICATE -- CONTINUED

                                       6
<PAGE>   7
SIGNATURE MEDALLION GUARANTEED:

        Signatures must be medallion guaranteed by an "eligible guarantor
institution" as defined in Rule 17Ad-15 promulgated under the Securities
Exchange Act of 1934, as amended.

            _______________________________________________________

        The undersigned hereby certifies that (1) the Rights evidenced by this
Right Certificate are not beneficially owned by nor are they being exercised on
behalf of an Acquiring Person, an Interested Stockholder or an Affiliate or
Associate thereof (as such terms are defined in the Rights Agreement); and (2)
after due inquiry and to the best of the knowledge of the undersigned, the
undersigned did not acquire the Rights evidenced by this Right Certificate from
any Person who is or was an Acquiring Person, an Interested Stockholder, or an
Affiliate or Associate thereof.

                                              __________________________________
                                              Signature

            _______________________________________________________

                                     NOTICE

        The signature in the Form of Assignment or Form of Election to Purchase,
as the case may be, must conform to the name as written upon the face of this
Right Certificate in every particular, without alteration or enlargement or any
change whatsoever.

        In the event the certification set forth above in the Form of Assignment
or the Form of Election to Purchase, as the case may be, is not completed, the
Company and the Rights Agent will deem the beneficial owner of the Rights
evidenced by this Right Certificate to be an Acquiring Person or an Affiliate or
Associate thereof (as defined in the Rights Agreement) and such Assignment or
Election to Purchase will not be honored.


                                       7


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