<PAGE>
                                                                     EXHIBIT 3.3


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

                               CYTEL CORPORATION

                                      and

                    AMERICAN STOCK TRANSFER & TRUST COMPANY,
                                as Rights Agent

                                Rights Agreement

                           Dated as of March 19, 1993

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

<Table>
<Caption>
                                                                                        Page
                                                                                        ----
<S>                                                                                     <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.............    7.

Section 8. Cancellation and Destruction of Right Certificates........................    8.

Section 9. Availability of Preferred Shares..........................................    9.

Section 10. Preferred Shares Record Date.............................................    9.

Section 11. Adjustment of Purchase Price, Number of Shares or Number of Rights.......    9.

Section 12. Certificate of Adjusted Purchase Price or Number of Shares...............   16.

Section 13. Consolidation, Merger or Sale or Transfer of Assets or Earning Power.....   16.

Section 14. Fractional Rights and Fractional Shares..................................   19.

Section 15. Rights of Action.........................................................   20.

Section 16. Agreement of Right Holders...............................................   20.

Section 17. Right Certificate Holder Not Deemed a Stockholder........................   21.

Section 18. Concerning the Rights Agent..............................................   21.

Section 19. Merger or Consolidation or Change of Name of Rights Agent................   21.

Section 20. Duties of Rights Agent...................................................   22.
</Table>


                                       i.
<PAGE>
<Table>
<S>            <C>                                                          <C>
Section 21.    Change of Rights Agent....................................... 24.

Section 22.    Issuance of New Right Certificates........................... 25.

Section 23.    Redemption................................................... 25.

Section 24.    Exchange..................................................... 26.

Section 25.    Notice of Certain Events..................................... 28.

Section 26.    Notices...................................................... 29.

Section 27.    Supplements and Amendments................................... 29.

Section 28.    Determination and Actions by the Board of Directors, etc..... 30.

Section 29.    Successors................................................... 30.

Section 30.    Benefits of this Agreement................................... 30.

Section 31.    Severability................................................. 31.

Section 32.    Governing Law................................................ 31.

Section 33.    Counterparts................................................. 31.

Section 34.    Descriptive Headings......................................... 31.


Exhibit A -    Certificate of Designation

Exhibit B -    Form of Right Certificate

Exhibit C -    Summary of Rights to Purchase Preferred Shares
</Table>




                                      ii.
<PAGE>

                                RIGHTS AGREEMENT

     Agreement, dated as of March 19, 1993, between Cytel Corporation, a
Delaware corporation (the "Company"), and American Stock Transfer & Trust
Company ("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 hereinafter defined) of the Company outstanding at the close of
business on April 8, 1993 (the "Record Date"), each Right representing the
right to purchase one one-hundredth of a Preferred Share (as 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 of the Distribution Date, the Redemption Date and the Final Expiration
Date (as such terms are hereinafter defined).

     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 of the
Company then outstanding, but shall not include the Company, any Subsidiary (as
such term is hereinafter defined) of the Company, any employee benefit plan of
the Company or any Subsidiary of the Company, or any entity holding Common
Shares for or pursuant to the terms of any such plan. Notwithstanding the
foregoing, no Person shall become an "Acquiring Person" 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 of the Common Shares of the Company then
outstanding; provided, however, that if a Person shall become the Beneficial
Owner of 15% or more of the Common Shares of the Company then outstanding by
reason of share purchases by the Company and shall, after such share purchases
by the Company, become the Beneficial Owner of any additional Common Shares of
the Company, then such Person shall be deemed to be an "Acquiring Person."
Notwithstanding the foregoing, if the Incumbent Board of Directors of the
Company (as hereinafter defined) determines in good faith that a Person who
would otherwise be an "Acquiring Person," as defined pursuant to the foregoing
provisions of this paragraph (a), has become such inadvertently, and such Person
divests as promptly as practicable 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.


                                       1.

<PAGE>
     (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 beneficially owns, directly or indirectly;

          (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)) or disposing of any securities of
     the Company.

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.


                                       2.
<PAGE>
     (d)  "Business Day" shall mean any day other than a Saturday, a Sunday, or
a day on which banking institutions in the State of California are authorized
or obligated by law or executive order to close.

     (e)  "Change of Control" shall mean:

          (i)  The acquisition (other than from the Company) by any person,
     entity or "group," within the meaning of Section 13(d)(3) or 14(d)(2) of
     the Exchange Act, (excluding, for this purpose, the Company or its
     subsidiaries, or any employee benefit plan of the Company or its
     subsidiaries which acquires beneficial ownership of voting securities of
     the Company) of beneficial ownership, (within the meaning of Rule 13d-3
     promulgated under the Exchange Act) of 50% or more of either the then
     outstanding Common Shares or the combined voting power of the Company's
     then outstanding voting securities entitled to vote generally in the
     election of directors; or

          (ii) Individuals who, as of the date hereof, constitute the Board (as
     of the date hereof the "Incumbent Board") cease for any reason to
     constitute at least a majority of the Board, provided that any person
     becoming a director subsequent to the date hereof whose election, or
     nomination for election by the Company's stockholders, was approved by a
     vote of at least a majority of the directors then comprising the Incumbent
     Board (other than an Affiliate or Associate of an Acquiring Person) shall
     be, for purposes of this Agreement, considered as though such person were a
     member of the Incumbent Board; or

          (iii) Approval by the stockholders of the Company of a reorganization,
     merger, or consolidation, in each case, with respect to which persons who
     were the stockholders of the Company immediately prior to such
     reorganization, merger or consolidation do not immediately thereafter, own
     more than 50% of the combined voting power entitled to vote generally in
     the election of directors of the reorganized, merged or consolidated
     company's then outstanding voting securities, or a liquidation or
     dissolution of the Company or of the sale of all or substantially all of
     the assets of the Company.

     (f)  "Close of Business" on any given date shall mean 5:00 p.m., San
Francisco time, on such date; provided, however, that if such date is not a
Business Day it shall mean 5:00 p.m., San Francisco time, on the next
succeeding Business Day.

     (g)  "Common Shares" when used with reference to the Company shall mean
the shares of common stock, par value $.01 per share, of the Company. "Common
Shares" when used with 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.

     (h)  "Distribution Date" shall have the meaning set forth in Section 3
hereof.


                                       3.
<PAGE>

     (i)  "Final Expiration Date" shall have the meaning set forth in Section 7
hereof.

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

     (k)  "Preferred Shares" shall mean shares of Series A Junior Participating
Preferred Stock, par value $0.01 per share, of the Company having the rights,
privileges and preferences set forth in the Form of Certificate of
Determination of Preferences attached to this Agreement as Exhibit A.

     (l)  "Redemption Date" shall have the meaning set forth in Section 7
hereof.

     (m)  "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.

     (n)  "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.

     Section 2. Appointment of Rights Agent. The Company hereby appoints the
Rights Agent to act as agent for the Company and the holders of the Rights
(who, in accordance with Section 3 hereof, shall prior to the Distribution Date
also be the holders of the Common Shares) 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 tenth day after 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 the consummation of which
would result in any Person becoming the Beneficial Owner of Common Shares
aggregating 15% or more of the then outstanding Common Shares (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 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



                                       4.
<PAGE>
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. 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 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 Cytel Corporation and America Stock
          Transfer & Trust Company, dated as of March 19, 1993, 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 Cytel Corporation. 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. Cytel Corporation 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 (as defined in the Rights Agreement) shall become
          null and void.

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


                                       5.
<PAGE>
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 cancelled and retired
so that the Company shall not be entitled to exercise any Rights associated
with the Common Shares which are no longer outstanding.

     Section 4. Form of Right Certificates. 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 on which the Rights may from time to
time be listed, or to conform to usage. Subject to the provisions of Section 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.

     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 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 Rights 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.


                                       6.
<PAGE>
     Section 6.  Transfer, Split Up, Combination and Exchange of Right
Certificates; Mutilated, Destroyed, Lost or Stolen Right Certificates. Subject
to the provisions of Section 14 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 (other than Right Certificates representing
Rights that have become void pursuant to Section 11(a)(ii) hereof or that have
been exchanged pursuant to Section 24 hereof) 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. Thereupon the Rights Agent shall 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 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.

     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 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 the Preferred Share (or such other number of share or other
securities) as to which the Rights are exercised, at or prior to the earliest
of (i) the close of business on March 19, 2003 (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 for each one one-hundredth of a Preferred Share
pursuant to the exercise of a Right shall initially be $80, shall be subject to
adjustment from time to time as provided in Section 11 and 13 hereof and shall
be payable in lawful money of the United States of America in accordance with
paragraph (c) below.


                                       7.
<PAGE>

     (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) 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.

     (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 cancelled form,
or, if delivered or surrendered to the Rights Agent, shall be cancelled by it,
and no Right Certificates shall be issued in lieu thereof except as expressly
permitted by any of the provisions of this Rights Agreement. The Company shall
deliver to the Rights Agent for cancellation and retirement, and the Rights
Agent shall so cancel and retire,



                                       8.
<PAGE>
any other Right Certificate purchased or acquired by the Company otherwise than
upon the exercise thereof. The Rights Agent shall deliver all cancelled Right
Certificates to the Company, or shall, at the written request of the Company,
destroy such cancelled 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 it will take all such action as may be necessary to ensure that all
Preferred Shares 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.

     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.

     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 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.


                                       9.
<PAGE>
     (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, he 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), 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).

     (ii)  Subject to Section 24 of this Agreement, in the event any Person
shall become an Acquiring Person, each holder of a Right shall, for a period of
60 days after the expiration or termination of the redemption option set forth
in Section 23(b) (provided 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 of the Company as shall equal 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 and
dividing that product by (B) 50% of the then current per share market price of
the Company's 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


                                      10.

<PAGE>
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) 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 cancelled.

        (iii) In the event that there shall not be sufficient Common Shares
issued but not outstanding or authorized but unissued 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 additional
Common Shares for issuance upon exercise of the Rights. In the event that the
Company shall, after a good faith effort, be unable to take all such action as
may be necessary to authorize such additional Common Shares, the Company shall
substitute, for each Common Share that would otherwise be issuable upon exercise
of a Right, a number of Preferred Shares or fraction thereof such that the
current per share market price of one Preferred Share multiplied by such number
or fraction thereof is equal to the current per share market price of one Common
Share as of the date of issuance of such Preferred Shares or fraction thereof;
provided, however, that if the Company is further unable to cause the
authorization of a sufficient number of Preferred Shares, then, in the event the
Rights become so exercisable, the Board of Directors may, but shall not be
required to, with respect to each Right (A) pay cash in an amount equal to the
Purchase Price, in lieu of issuing Common Shares and requiring payment
therefor, or (B) issue debt or equity securities or a combination thereof,
having a value equal to the Current Value of the Common Shares (as defined
hereinafter), where the value of such securities shall be determined by a
nationally recognized investment banking firm selected by the Board of Directors
of the Company, and require the payment of the Purchase Price, or (C) deliver
any combination of cash, property, Common Shares, Preferred Shares and/or other
securities having a value equal to the Current Value, and require payment of all
or any requisite portions of the Purchase Price. The Current Value shall be the
product of the current market price per share of Common Shares (determined
pursuant to Section 11(d) on the date of the occurrence of the event described
above in subparagraph (ii)) multiplied by the number of Common Shares for which
the Right otherwise would be exercisable if there were


                                      11.
<PAGE>

sufficient shares available. To the extent that the Company determines that
some action need be taken pursuant to the second sentence of this subparagraph
(iii), the Board of Directors may temporarily suspend the exercisability of the
Rights for a period of up to 45 days following the date on which the event
described in Section 11(a)(ii) shall have occurred, in order to seek any
authorization of additional Common Shares and/or to decide the appropriate form
of distribution to be made pursuant to the above provision and to determine the
value thereof. 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 rights,
privileges and preferences 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 defined in Section 11(d)) 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 determined by multiplying the
Purchase Price in effect immediately prior to such record date by



                                      12.
<PAGE>
a fraction, the numerator of which shall be the then current per share market
price of the Preferred Shares (as defined in Section 11(d)) 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 exdividend 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, if the Security is not listed or
admitted to trading on any national securities exchange, 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. The term "Trading Day" shall mean a day on which
the principal national securities exchange on which the Security 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.


                                       13.
<PAGE>
          (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). 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) (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-millionth 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 Section 11(a) through (c), inclusive, and the
provisions of Sections 7, 9, 10, 13 and 14 with respect to the Preferred Shares
shall apply on the 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), upon each adjustment of the Purchase Price as a result of the
calculations made in Section 11(b) and (c), 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-hundredths 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 product so obtained by the Purchase Price
in effect immediately after such adjustment of the Purchase Price.


                                      14.
<PAGE>
     (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 addition 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 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


                                      15.
<PAGE>
or other appropriate instrument evidencing such holder's right to receive such
additional shares upon the occurrence of the event requiring such adjustment.

     (m) 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.

     (n) 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(n) shall be made successively whenever such a
dividend is declared or paid or such a subdivision, combination or consolidation
is effected.

     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 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, directly or
indirectly (x) the Company shall consolidate with, or merge with and into, any
other Person, (y) any Person shall consolidate with the Company, or merge with
and into the Company, and the

                                      16.
<PAGE>
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 other
Person, then, and in each such case, proper provision shall be made so that (i)
following the Distribution Date, each holder of a Right, subject to Section
7(e), 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 shares of freely tradeable Common Shares of the Principal Party
(as 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 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 (x) or (y) of the
     first sentence of Section 13(a), the Person that is the issuer of any
     securities into which Common Shares of the Company 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 (including, 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 in Section 13(a), the Person that is the party receiving the
     greatest portion of the assets or earning power transferred pursuant to
     such transaction or transactions;


                                      17.
<PAGE>
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) in case 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) in case 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" or 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 shares of its 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 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 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) prepare and file a registration statement under the
        Securities Act of 1933 (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;

                (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; and

                (iii) 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.


                                      18.

<PAGE>
     (d) After the Shares Acquisition 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, if 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. The Company shall not consummate
any such consolidation, merger or sale 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 subsection.

     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 for any day shall be the last
sale price, regular way, or, in case no such stale 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, if the Rights are not
listed or admitted to trading on any national securities exchange, 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 rights, privileges and preferences 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


                                      19.

<PAGE>

one-hundredth of a Preferred Share, the Company shall pay to the registered
holders of Rights 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 closing price of a
Preferred Share (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.

     (c)  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 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


                                      20.
<PAGE>
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 on any other
securities of the Company which 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 at set forth in
Section 20 hereof.

     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


                                      21.
<PAGE>

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 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


                                      22.

<PAGE>
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 Section
3, 11, 13, 23 or 24, or the ascertaining of the existence of facts that would
require any such change or adjustment (except with respect to the exercise of
Rights evidenced by Right Certificates after receipt of a certificate pursuant
to Section 12 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 instruction 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
Rights 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 nay 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 applicable
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,

                                      23.
<PAGE>
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 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 or 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 a
corporation 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. 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 delivery 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



                                      24.
<PAGE>
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 accordance with the provisions of this Agreement.

     Section 23. Redemption.

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

     (b)  The Board of Directors of the Company may, at its option, at any time
prior to the earliest of (i) the close of business on (A) the twentieth day
following the Shares Acquisition Date or (B) such date or dates more than 20
days after the Shares Acquisition Date to which such option may be extended by
the Board of Directors (for one or more successive 10 day periods) by vote(s)
first taken or written consent(s) first given on or prior to the twentieth day
following the Shares Acquisition Date and, thereafter, on or prior to the
completion of any such 10 day extension or extensions (or, if the Shares
Acquisition Date shall have occurred prior to the Record Date, the close of
business on (A) the twentieth day following the Record Date or (B) such date or
dates more than 20 days after the Record Date to which such option may be
extended by the Board of Directors (for one or more successive 10 day periods)
by vote(s) first taken or written consent(s) first given on or prior to the
twentieth day following the Record Date and, thereafter, on or prior to the
completion of any such 10 day extension or extensions); (ii) such time on or
after the Shares Acquisition Date as there shall have occurred a Change of
Control; or (iii) the Final Expiration Date, redeem all but not less then all
the then outstanding Rights at a redemption price of $.01 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 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 Company's redemption option pursuant
to this Section 23 shall terminate at such time on or after the Shares
Acquisition Date as there shall occur a Change of Control. 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 hereunder.


                                      25.
<PAGE>

     (c)  Immediately upon the action of the Board of Directors of the Company
ordering the redemption of the Rights pursuant to subsection (b) of this
Section 23, 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 subsection (b) 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. 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 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.

     (b)  Immediately upon the action of the Board of Directors of the Company
ordering the exchange of any Rights pursuant to subsection (a) of this Section
24 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



                                      26.
<PAGE>

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.
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 the event that there shall not be sufficient Common Shares issued
but not outstanding or authorized but unissued to permit any exchange of Rights
as contemplated in accordance with this Section 24, the Company shall take all
such action as may be necessary to authorize additional Common Shares for
issuance upon exchange of the Rights. In the event that the Company shall, after
a good faith effort, be unable to take all such action as may be necessary to
authorize such additional Common Shares, the Company shall substitute, for each
Common Share that would otherwise be issuable upon exchange of a Right, a number
of Preferred Shares or fraction thereof such that the current per share market
price of one Preferred Share multiplied by such number or fraction thereof
multiplied by such number or fraction is equal to the current per share market
price of one Common Share as of the date of issuance of such Preferred Shares or
fraction thereof; provided, however, that if the Company is further unable to
cause the authorization of a sufficient number of additional Common Shares,
then, in the event the Rights become so exchangeable, the Board of Directors
may, but shall not be required to, with respect to each Right (A) pay cash in an
amount equal to the current per share market price of one Common Share
(determined pursuant to Section 11(d) on the date of the occurrence of the event
described in Section 11(a)(ii)) in exchange for each Right, in lieu of issuing
Common Shares, or (B) issue debt or equity securities or a combination thereof,
having a value equal to the current per share market price of one Common Share
(determined pursuant to Section 11(d) on the date of the occurrence of the event
described in Section 11(a)(ii)) where the value of such securities shall be
determined by a nationally recognized investment banking firm selected by the
Board of Directors of the Company, in exchange for each Right, or (C) deliver
any combination of cash, property, Common Shares and/or other securities having
a value equal to the current per share market price of one Common Share
(determined pursuant to Section 11(d) on the date of the occurrence of the event
described in Section 11(2)(ii)) in exchange for each Right. To the extent that
the Company determines that some action need be taken pursuant to the second
sentence of this Section 24(c), the Board of Directors may temporarily suspend
the exercisability of the Rights for a period of up to 45 days following the
date on which the event described in Section 11(a)(ii) shall have occurred, in
order to seek any authorization of additional Common Shares and/or to decide the
appropriate form of distribution to be made pursuant to the above provision and
to determine the value thereof. 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.


                                      27.
<PAGE>

     (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
subsection (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 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 rights, privileges and preferences 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 the closing price of a
Preferred 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



                                      28.
<PAGE>
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 bo 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.

     (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:

                 Cytel Corporation
                 3525 John Hopkins Court
                 San Diego, CA  92121
                 Attention: 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:

                 American Stock Transfer & Trust Company
                 40 Wall Street
                 New York, NY  10005
                 Attention: Shareholder Services Division

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. The Company may from time to time
supplement or amend this Agreement without the approval of any holders of Right
Certificates in order to cure any ambiguity, to correct or supplement any
provision contained herein which may be defective or inconsistent with any other
provisions herein, or to make any other provisions with respect to the Rights
which the Company may deem necessary or desirable, any


                                      29.
<PAGE>
such supplement or amendment to be evidenced by a writing signed by the
Company and the Rights Agent; provided, however, that from and after such time
as any Person becomes an Acquiring Person, this Agreement shall not be amended
in any manner which would adversely affect the interests of the holders of
Rights. Without limiting the foregoing, the Company may at any time prior to
such time as any Person becomes an Acquiring Person amend this Agreement to
lower the thresholds set forth in Sections 1(a) and 3(a) hereof from 15% to any
percentage which is (i) greater than the largest percentage of the outstanding
Common Shares then known by the Company to be beneficially owned by any Person
(other than the Company, any employee benefit plan of the Company or any
Subsidiary, or any entity holding Common Shares for or pursuant to the terms of
any such plan) and (ii) not less than 10%. Upon delivery of a certificate from
an appropriate officer of the Company which states that the proposed supplement
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 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 Right Certificates, and (y) not subject the Board to any liability to
the holders of the Right Certificates.

     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.



                                      30.
<PAGE>
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.

     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.

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

                                         CYTEL CORPORATION

Attest:


By: /s/ [SIGNATURE ILLEGIBLE]            By: [SIGNATURE ILLEGIBLE]
   ---------------------------------        ---------------------------------

Title: Vice President and                Title: President and
       General Counsel                          Chief Executive Officer
      ------------------------------           ------------------------------


                                         AMERICAN STOCK TRANSFER & TRUST COMPANY

Attest:


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

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


                                      31.
<PAGE>
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.

     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.

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

                                         CYTEL CORPORATION

Attest:


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

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



                                         AMERICAN STOCK TRANSFER & TRUST COMPANY

Attest:


By: /s/ [SIGNATURE UNINTELLIGIBLE]       By: [SIGNATURE UNINTELLIGIBLE]
   ---------------------------------        ---------------------------------

Title: Vice President                    Title: Vice President
      ------------------------------           ------------------------------


                                      31.
<PAGE>
                                                                      EXHIBIT A
                                                                      ---------

                                      FORM

                                       of

                           CERTIFICATE OF DESIGNATION

                                       of

                 SERIES A JUNIOR PARTICIPATING PREFERRED STOCK

                                       of

                               CYTEL CORPORATION

                        (Pursuant to Section 151 of the
                       Delaware General Corporation Law)



    Cytel Corporation, a corporation organized and existing under the General
Corporation Law of the State of Delaware (hereinafter called the "Corporation"),
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 December 4, 1992:

    RESOLVED, that pursuant to the authority granted to and vested in the Board
of Directors of the Corporation in accordance with the provisions of its
Restated Certificate of Incorporation, the Board of Directors hereby creates a
series of Preferred Stock, par value $.01 share, of the Corporation and hereby
states the designation and number of shares, and fixes the relative rights,
preferences, preferences and limitations thereof (in addition to the provisions
set forth in the Restated Certificate of Incorporation of the Corporation, which
are applicable to the Preferred Stock of all classes and series), as follows:

    Series A Junior Participating Preferred Stock:

    Section 1. Designation and Amount. Three Hundred Thousand (300,000) shares
of Preferred Stock, $.01 par value, are designated "Series A Junior
Participating Preferred Stock" with the rights, preferences, privileges and
restrictions specified herein (the "Series A 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 Series A
Preferred



                                      A-1.
<PAGE>
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 Corporation convertible into Series A Preferred Stock.

     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
     Series A Preferred Stock with respect to dividends, the holders of shares
     of Series A Preferred Stock, in preference to the holders of Common Stock,
     par value $.01 per share (the "Common Stock"), of the Corporation, 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 March,
     June, September and December 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 Series A Preferred Stock, in an amount per share
     (rounded to the nearest cent) equal to the greater of (a) $1.00 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 Series A Preferred Stock. In the event the
     Corporation 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 Series A
     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 Corporation shall declare a dividend or distribution on the
     Series A 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 Series A Preferred Stock shall nevertheless by
     payable on such subsequent Quarterly Dividend Payment Date.


                                      A-2.
<PAGE>
               (C)  Dividends shall begin to accrue and be cumulative on
          outstanding shares of Series A 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 determinator of
          holders of shares of Series A 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 Series A 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 Series A 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 Series A Preferred
Stock shall have the following voting rights:

               (A)  Subject to the provision for adjustment hereinafter set
          forth, each share of Series A Preferred Stock shall entitle the holder
          thereof to 100 votes on all matters submitted to a vote of the
          stockholders of the Corporation. In the event the Corporation 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 Series A 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 Determination of Preferences creating a series of
          Preferred Stock or any similar stock, or by law, the holders of shares
          of Series A Preferred Stock and the holders of shares of Common Stock
          and any other capital stock of the Corporation having general voting
          rights shall vote together as one class on all matters submitted to a
          vote of stockholders of the Corporation.

               (C)  Except as set forth herein, or as otherwise provided by law,
          holders of Series A 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.



                                        A-3.
<PAGE>
     Section 4.  Certain Restrictions.

          (A)  Whenever quarterly dividends or other dividends or distributions
     payable on the Series A 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 Series A Preferred
     Stock outstanding shall have been paid in full, the Corporation 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 Series A 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 Series A Preferred Stock,
     except dividends paid ratably on the Series A 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 Series A Preferred Stock,
     provided that the Corporation may at any time redeem, purchase or otherwise
     acquire shares of any such junior stock in exchange for shares of any stock
     of the Corporation ranking junior (either as to dividends or upon
     dissolution, liquidation or winding up) to the Series A Preferred Stock; or

               (iv)   redeem or purchase or otherwise acquire for consideration
     any shares of Series A Preferred Stock, or any shares of stock ranking on a
     parity with the Series A 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 Corporation shall not permit any subsidiary of the
     Corporation to purchase or otherwise acquire for consideration any shares
     of stock of the Corporation unless the Corporation 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 Series A Preferred Stock
purchased or otherwise acquired by the Corporation 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


                                      A-4.
<PAGE>
Restated Certificate of Incorporation, or in any other Certificate of
Determination of Preferences 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 Corporation, 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 Series A Preferred Stock unless,
prior thereto the holders of shares of Series A 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 holder of shares of Series A 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 Series A Preferred Stock,
except distributions made ratably on the Series A 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 Corporation 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 Series A 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 Corporation 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
Series A 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 Corporation 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 Series A 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.


                                        A-5.
<PAGE>
    Section 8. No Redemption. The Shares of Series A. Preferred Stock shall not
               -------------
be redeemable.

    Section 9. Rank. The Series A 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 Corporations's Preferred Stock.


    Section 10. Amendment. The Restated Certificate of Incorporation of the
                ---------
Corporation shall not be amended in any manner which would materially alter or
change the powers, preferences or special rights of the Series A 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 Series A Preferred
Stock, voting together as a single class.

    IN WITNESS WHEREOF the undersigned have executed this certificate as of
March 19, 1993.




                                       -------------------------------------
                                       Jay D. Kranzler
                                       President and Chief Executive Officer



                                       -------------------------------------
                                       Martin H. Goldstein
                                       Secretary



                                      A-6.



<PAGE>
                                                                       EXHIBIT B
                                                                       ---------

                           Form of Right Certificate

Certificate No. R-                                                ______Rights

     NOT EXERCISABLE AFTER MARCH 19, 2003 OR EARLIER IF REDEMPTION OR EXCHANGE
     OCCURS. THE RIGHTS ARE SUBJECT TO REDEMPTION AT $.01 PER RIGHT AND TO
     EXCHANGE ON THE TERMS SET FORTH IN THE RIGHTS AGREEMENT.


                               Right Certificate

                               CYTEL 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 March 19, 1993 (the "Rights Agreement"), between Cytel
Corporation, a Delaware corporation (the "Company"), and American Stock
Transfer & Trust Company (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., San Diego Time, on March 19,2003 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 A Junior Participating Preferred Stock, par value $.01 per
share  (the "Preferred Shares"), of the Company, at a purchase price of $80 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 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 Price
set forth above, are the number and Purchase Price as of March 19, 1993 based
on the Preferred Shares as constituted at such date.

     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 of this Right Certificate are subject to modification
and adjustment upon happening of certain events.


                                      B-1.


<PAGE>
     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
$.01 per Right or (ii) may be exchanged in whole or in part for shares of the
Company's Common Stock or Preferred Shares, par value $.01 per share.

     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.



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

ATTEST:                                         CYTEL CORPORATION



                                                By
----------------------------                      ------------------------------



Countersigned:



AMERICAN STOCK TRANSFER &
TRUST COMPANY
as Rights Agent



By
  --------------------------
   Authorized Signature



                                      B-3.
<PAGE>
                   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



Signature Guaranteed:

     Signatures must be 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 the Rights evidenced by this Right
Certificate are not beneficially owned by an Acquiring Person or an Affiliate
or Associate thereof (as defined in the Rights Agreement).



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




                                      B-4.
<PAGE>
             Form of Reverse Side of Right Certificate -- continued

                          FORM OF ELECTION TO PURCHASE

                 (To be executed if holder desires to exercise
                 Rights represented by the Right Certificate.)

To CYTEL CORPORATION

     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



                                      B-5.

<PAGE>
             Form of Reverse Side of Right Certificate -- continued



Signature Guaranteed:

     Signatures must be 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 the Rights evidenced by this Right
Certificate are not beneficially owned by an Acquiring Person or an Affiliate
or Associate thereof (as defined in the Rights Agreement)



                                        ----------------------------------
                                        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-6.
<PAGE>
                                                                       EXHIBIT C
                                                                       ---------


                         SUMMARY OF RIGHTS TO PURCHASE
                                PREFERRED SHARES


     On March 19, 1993, the Board of Directors of Cytel Corporation, (the
"Company") declared a dividend of one preferred share purchase right (a "Right")
for each outstanding share of common stock, par value $.01 per share (the
"Common Shares"), of the Company. The dividend is payable on April 8, 1993 ( 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 A Junior Participating Preferred Stock, par value $.01 per share (the
"Preferred Shares"), of the Company at a price of $80 per one one-hundredth of a
Preferred Share (the "Purchase Price"), subject to adjustment. The description
and terms of the Rights are set forth in a Rights Agreement dated as of March
19,1993 (the "Rights Agreement"), between the Company and American Stock
Transfer & Trust Company as Rights Agent (the "Rights Agent").

     Initially, the Rights will be evidenced by the stock certificates
representing Common Shares then outstanding, and no separate Right Certificates,
as defined, will be distributed. Until the earlier to occur of (i) 10 days
following a public announcement that a person or group affiliated or associated
persons (an "Acquiring Person") has acquired beneficial ownership of 15% or more
of the outstanding Common Shares 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 group of affiliated persons becomes an Acquiring Person) following the
commencement of, or announcement of an intention to make, a tender offer or
exchange offer the consummation of which would result in the beneficial
ownership by a person or group of 15% or more of the outstanding Commons 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 with a copy
of this Summary of Rights attached thereto.

     The Rights Agreement provides that, until the Distribution Date (or earlier
redemption or expiration of the Rights), the Rights will be transferred 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 of 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 practicable
following the Distribution Date, separate certificates evidencing the Rights
("Right


                                      C-1.
<PAGE>
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.

     The Rights are not exercisable until the Distribution Date. The Rights will
expire on March 19, 2003 (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.

     The Purchase Price payable, and the number of Preferred Shares or other
securities or property issuable, 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 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.

     Preferred Shares purchasable upon  exercise of Rights will not be
redeemable. Each Preferred Share will be entitled to a minimum preferential
quarterly dividend of 100 times the dividend payment of $1 per share but will be
entitled to an aggregate dividend declared per Common Share. In the event of
liquidation, the holders of the Preferred Shares will be entitled to an
aggregate 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 Share. 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 rank junior to all other series of the
Company's Preferred stock.

     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, 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


                                      C-2
<PAGE>
market value of two times the exercise price of the Right. 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 (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.

     At any time after any Person becomes an Acquiring Person and prior to the
acquisition by such person or group of 50% of 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 one one-hundredth of a
Preferred Share (or of a share of a class or series of the Company's preferred
stock having equivalent rights, preferences and privileges), per Right (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 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.

At any time prior to the earliest of (i) the close of business on the twentieth
day following the first public announcement that a person has become an
Acquiring Person (subject to extension for one or more successive 10 day periods
pursuant to the Rights Agreement), (ii) such time on or after the first public
announcement that a person has become an Acquiring Person as there shall have
occurred a Change of Control (as defined in the Rights Agreement) of the
Company, or (iii) the final Extension Date, the Board of Directors of the
Company may redeem the Rights in whole, but not in part, at a price of $.01 per
Right (the "Redemption Price"). the redemption of the Rights may be made
effective at such time on such basis 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.

     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, including an amendment
to lower certain thresholds described above to any percentage which is (i)
greater than the largest percentage of the outstanding Common Shares then known
to the Company to be beneficially owned by any person or group of affiliated or
associated persons (other than the Company, any Subsidiary of the Company,
employee benefit plans of any Company of any Subsidiary, or any entity holding
Common Shares pursuant to the terms of any such plan) and (ii) not less not 10%,
except that from and after such time as any person or group of affiliated or
associated persons becomes an Acquiring Person no such amendment may adversely
affect the interests of the holders of the Rights.

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.


                                      C-3.
<PAGE>
     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 March
19, 1993. A copy of the Rights Agreement is available free of charge from the
Company by writing to: Corporate Secretary, Cytel Corporation, 3525 John
Hopkins Court, San Diego, California 92121. This summary description of the
Rights does not purport 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>

                                   EXHIBIT 2



                                       2.
<PAGE>
                                         April 8, 1993



To Our Stockholders:

     Your Board of Directors has adopted a Preferred Share Purchase Rights Plan
under which Cytel Corporation ("Cytel") will issue Rights with its Common stock.
We believe that this Plan will provide protection to the stockholders from many
of the takeover abuses prevalent today. The terms of the Plan are set forth in a
Rights Agreement. A summary of the Rights Agreement, which you may wish to
attach to your share certificate, is attached to this letter.

     The Rights to be issued under the Plan contain provisions to protect
stockholders in the event of an unsolicited attempt to acquire Cytel, including
a gradual accumulation of shares in the open market, a partial or two-tier
tender offer that does not treat all stockholders equally, a squeeze-out merger
and other abusive takeover tactics which the Board believes are not in the best
interests of stockholders. these tactics unfairly pressure stockholders, squeeze
them out of their investment without giving them any real choice and deprive
them of the full value of their shares. Over 1,500 other companies have issued
rights to protect stockholders against these tactics. We consider the Rights to
be the best available means of protecting both your right to retain your equity
investment in Cytel and the full value of that investment, while not foreclosing
a fair acquisition bid for Cytel.

     The Plan is not intended to prevent a takeover of Cytel and will not do so.
However, it should deter any attempt to acquire Cytel in a manner or on terms
not approved by the Board and, in some cases, by the stockholders. The Plan is
designed to deal with the very serious problem of another person or company
using abusive tactics to deprive Cytel's Board and stockholders of any real
opportunity to determine the destiny of Cytel.

     The Rights will trade automatically with shares of Cytel's Common Stock and
are not exercisable except as provided in the Rights Agreement. However, as more
fully described in the Summary attached to this letter, ten days after the
announcement that a person or group has acquired 15% or more of Cytel's shares,
or ten business days after the announcement that a person or group has commenced
a tender offer the consummation of which would result in such person or group
owning 15% or more of the shares (even if no purchases actually occur), the
Rights will become exercisable, and separate certificates representing the
rights will be distributed. We expect that the Rights will begin to trade
independently from Cytel's shares at that time. At no time will the Rights have
any voting power.



                                        1.
<PAGE>
April 8, 1993
Page 2



     In adopting the Plan, we have expressed our continued confidence in the
future and our determination that you, our stockholders, be given every
opportunity to participate fully in that future.

     On behalf of the Board of Directors,



                                           -------------------------------------
                                           Jay D. Kranzler
                                           President and Chief Executive Officer


                                       2.
<PAGE>
                         SUMMARY OF RIGHTS TO PURCHASE
                                PREFERRED SHARES

     On March 19, 1993 the Board of Directors of Cytel Corporation (the
"Company") declared a dividend of one preferred share purchase right (a "Right")
for each outstanding share of common stock, par value $.01 per share (the
"Common Shares"), of the Company. The dividend is payable on April 8, 1993 (the
"Record Date") to the stockholders of record on that date. Each Right entitles
the register holder to purchase from the Company one one-hundredth of a share of
Series A Junior Participating Preferred Stock, par value $.01 per share (the
"Preferred Shares"), of the Company at a price of $80 per one one-hundredth of a
Preferred Share (the "Purchase Price"), subject to adjustment. The description
and terms of the Rights are set forth in a Rights Agreement dated as of March
19, 1993 (the "Rights Agreement"), between the Company and American Stock
Transfer & Trust Company, as Rights Agent (the "Rights Agent").

     Initially, the Rights will be evidenced by the stock certificates
representing Common Shares then outstanding, and no separate Right Certificates,
as defined, will be distributed. Until the earlier to occur of (i) 10 days
following a public announcement that a person or group of affiliated or
associated persons (an "Acquiring Person") has acquired beneficial ownership of
15% or more of the outstanding Common Shares 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 group of affiliated persons becomes an Acquiring
Person) following the commencement of, or announcement of an intention to make,
a tender offer or exchange offer the consummation of which would result in the
beneficial ownership by a person or group 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
with a copy of this Summary of Rights attached thereto.

     The Rights Agreement provides that, until the Distribution Date (or
earlier redemption or expiration of the Rights), the Rights will be transferred
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
practicable following the Distribution Date, separate certificates evidencing
the Rights ("Rights 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.
<PAGE>
     The Rights are not exercisable until the Distribution Date. The Rights
will expire on March 19, 2003 (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.

     The Purchase Price payable, and the number of Preferred Shares or other
securities or property issuable, 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
of 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 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 combination of the Common Shares occurring, in any such 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 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 rank junior to
all other series of the Company's preferred stock.

     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, 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. 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 (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.

                                       2
<PAGE>
     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 one one-hundredth
of a Preferred Share (or of a share of a class or series of the Company's
preferred stock having equivalent rights, preferences and privileges), per Right
(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 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.

     At any time prior to the earliest of (i) the close of business on the
twentieth day following the first public announcement that a person has become
an Acquiring Person (subject to extension for one or more successive 10 day
periods pursuant to the Rights Agreement), (ii) such time on or after the first
public announcement that a person has become an Acquiring Person as there shall
have occurred a Change of Control (as defined in the Rights Agreement) of the
Company, or (iii) 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 $.01 per
Right (the "Redemption Price"). The redemption of the rights may be made
effective at such time on such basis with such conditions as the Board of
Directors in tis 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.

     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, including an amendment
to lower certain thresholds described above to any percentage which is (i)
greater than the largest percentage of the outstanding Common Shares then known
to the Company to be beneficially owned by any person or group of affiliated or
associated persons (other than the Company, any Subsidiary of the Company,
employee benefit plans of any Company or any Subsidiary, or any entity holding
Common Shares pursuant to the terms of any such plan) and (ii) not less than
10%, except that from and after such time as any person or group of affiliated
or associated persons becomes an Acquiring Person no such amendment may
adversely affect the interests of the holders of the Rights.

     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 receive dividends.


                                       3.
<PAGE>
     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 March
19, 1993. A copy of the Rights Agreement is available free of charge from the
Company by writing to: Corporate Secretary, Cytel Corporation, 3525 John
Hopkins Court, San Diego, California 92121. This summary description of the
rights does not purport to be complete and is qualified in its entirety by
reference to the Rights Agreement, which is hereby incorporated herein by
reference.
<PAGE>
                          AMENDMENT TO RIGHTS AGREEMENT


        This AMENDMENT (the "Amendment") to the Rights Agreement (the
"Agreement") entered into as of March 19, 1993, by and between CYTEL
CORPORATION, a Delaware corporation (the "Company"), and AMERICAN STOCK TRANSFER
& TRUST COMPANY (the "Rights Agent"), is entered into as of June 29, 1999 (the
"Amendment Date").

                                    RECITALS

        WHEREAS, concurrently herewith, the Company is entering into certain
exchange agreements whereby G.D. Searle & Co. ("Searle") will acquire capital
stock of the Company (the "Exchange");

        WHEREAS, the parties desire to amend the Agreement in the manner set
forth in this Amendment to provide that the Exchange will not trigger the
issuance of Rights Certificates under the Agreement;


                                    AGREEMENT

        NOW, THEREFORE, in consideration of the benefits described in the
RECITALS hereto and the mutual promises hereinafter set forth, the parties
hereto agree as follows:

1.      Except as otherwise defined herein, capitalized terms used but not
        defined herein shall have the respective meanings given to them in the
        Agreement.

2.      Section 1(a) of the Agreement is hereby amended and restated in its
        entirety as follows:

            "(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 of the Company then outstanding,
            but shall not include the Company, any Subsidiary (as such term is
            hereinafter defined) of the Company, any employee benefit plan of
            the Company or any Subsidiary of the Company, or any entity holding
            Common Shares for or pursuant to the terms of any such plan.
            Notwithstanding the foregoing, no Person shall become an "Acquiring
            Person" 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 of the Common Shares of the Company then
            outstanding; provided, however, that if a Person shall become the
            Beneficial Owner of 15% or more of the Common Shares of the Company
            then outstanding by reason of share purchases by the Company and
            shall, after such share purchases by the Company, become the
            Beneficial Owner of any additional Common Shares of


<PAGE>


           the Company, then such Person shall be deemed to be an "Acquiring
           Person." Notwithstanding the foregoing, if the Incumbent Board of
           Directors of the Company (as hereinafter defined) determines in good
           faith that a Person who would otherwise be an "Acquiring Person," as
           defined pursuant to the foregoing provisions of this paragraph (a),
           has become such inadvertently, and such Person divests as promptly as
           practicable 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.

           In addition, G.D. Searle & Co., a Delaware corporation ("Searle"),
           shall not be deemed to be an "Acquiring Person" for purposes of this
           Agreement solely to the extent that Searle and any of its Affiliates
           or Associates (i) Beneficially Own the Company's capital stock as of
           the date hereof or (ii) acquire the Company's Common Shares in
           accordance with the terms of that certain Preferred Stock Exchange
           Agreement, dated July 1, 1999, between Searle and the Company or any
           documents executed in connection with or pursuant thereto, including,
           but not limited to, that certain Investor Rights Agreement, dated
           July 1, 1999, between Searle and the Company.

           Solely for the purposes of the foregoing, "Searle" shall include any
           entity which acquires all or substantially all of the business or
           assets of such entity."

3.      This Amendment shall be governed by and construed in accordance with the
        laws of the State of California.

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


                      [THIS SPACE INTENTIONALLY LEFT BLANK]



<PAGE>
IN WITNESS WHEREOF, the parties have executed this Amendment on the day and year
first written above.


     CYTEL CORPORATION                 AMERICAN STOCK TRANSFER &
                                       TRUST COMPANY



By:  /s/ Robert L. Roe                 By:
     -------------------------------      --------------------------------------
     Robert L. Roe, M.D.
     Acting President

<PAGE>
                          AMENDMENT TO RIGHTS AGREEMENT


        This AMENDMENT (the "Amendment") to the Rights Agreement (the
"Agreement") entered into as of March 19, 1993, as amended June 29, 1999, by and
between EPIMMUNE INC. (formerly Cytel Corporation), a Delaware corporation (the
"Company"), and AMERICAN STOCK TRANSFER & TRUST COMPANY (the "Rights Agent"), is
entered into as of February __, 2000 (the "Amendment Date").

                                    RECITALS

        WHEREAS, concurrently herewith, the Company is entering into a Common
Stock Purchase Agreement whereby State of Wisconsin Investment Board ("SWIB")
will acquire capital stock of the Company (the "Stock Purchase");

        WHEREAS, the parties desire to amend the Agreement in the manner set
forth in this Amendment to provide that the Stock Purchase will not trigger the
issuance of Rights Certificates under the Agreement.

                                    AGREEMENT

        NOW, THEREFORE, in consideration of the benefits described in the
RECITALS hereto and the mutual promises hereinafter set forth, the parties
hereto agree as follows:

5.      Except as otherwise defined herein, capitalized terms used but not
        defined herein shall have the respective meanings given to them in the
        Agreement.

6.      Section 1(a) of the Agreement is hereby amended and restated in its
        entirety as follows:

           "(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 of the Company then outstanding,
           but shall not include the Company, any Subsidiary (as such term is
           hereinafter defined) of the Company, any employee benefit plan of the
           Company or any Subsidiary of the Company, or any entity holding
           Common Shares for or pursuant to the terms of any such plan.
           Notwithstanding the foregoing, no Person shall become an "Acquiring
           Person" 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 of the Common Shares of the Company then
           outstanding; provided, however, that if a Person shall become the
           Beneficial Owner of 15% or more of the Common Shares of the Company
           then outstanding by reason of share


<PAGE>

           purchases by the Company and shall, after such share purchases by the
           Company, become the Beneficial Owner of any additional Common Shares
           of the Company, then such Person shall be deemed to be an "Acquiring
           Person." Notwithstanding the foregoing, if the Incumbent Board of
           Directors of the Company (as hereinafter defined) determines in good
           faith that a Person who would otherwise be an "Acquiring Person," as
           defined pursuant to the foregoing provisions of this paragraph (a),
           has become such inadvertently, and such Person divests as promptly as
           practicable 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.

           In addition, G.D. Searle & Co., a Delaware corporation ("Searle"),
           shall not be deemed to be an "Acquiring Person" for purposes of this
           Agreement solely to the extent that Searle and any of its Affiliates
           or Associates (i) Beneficially Own the Company's capital stock as of
           the date hereof or (ii) acquire the Company's Common Shares in
           accordance with the terms of that certain Preferred Stock Exchange
           Agreement, dated July 1, 1999, between Searle and the Company or any
           documents executed in connection with or pursuant thereto, including,
           but not limited to, that certain Investor Rights Agreement, dated
           July 1, 1999, between Searle and the Company. Solely for the purposes
           of the foregoing, "Searle" shall include any entity which acquires
           all or substantially all of the business or assets of such entity.

           In addition, State of Wisconsin Investment Board ("SWIB"), shall not
           be deemed to be an "Acquiring Person" for purposes of this Agreement
           solely to the extent that SWIB and any of its Affiliates or
           Associates (i) Beneficially Own the Company's capital stock as of the
           date hereof or (ii) acquire the Company's Common Shares in accordance
           with the terms of that certain Common Stock Purchase Agreement, dated
           February ____, 2000, between SWIB and the Company or any documents
           executed in connection with or pursuant thereto. Solely for the
           purposes of the foregoing, "SWIB" shall include any entity which
           acquires all or substantially all of the business or assets of such
           entity."

7.      This Amendment shall be governed by and construed in accordance with the
        laws of the State of California.

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



                      [THIS SPACE INTENTIONALLY LEFT BLANK]



<PAGE>
IN WITNESS WHEREOF, the parties have executed this Amendment on the day and year
first written above.

     EPIMMUNE INC.                             AMERICAN STOCK TRANSFER &
                                               TRUST COMPANY



By:  /s/ Deborah Schueren                      By:
     ---------------------------------------      ------------------------------
     Deborah Schueren                          Print Name:
     President and Chief Executive Officer                ----------------------
                                               Title:
                                                      --------------------------
<PAGE>
                          AMENDMENT TO RIGHTS AGREEMENT

        This AMENDMENT (the "Amendment") to the Rights Agreement (the
"Agreement") entered into as of March 19, 1993, as amended June 29, 1999 and
February 15, 2000, by and between EPIMMUNE INC. (formerly Cytel Corporation), a
Delaware corporation (the "Company"), and AMERICAN STOCK TRANSFER & TRUST
COMPANY (the "Rights Agent"), is entered into as of July 9, 2001.

                                    RECITALS

        WHEREAS, concurrently herewith, the Company is entering into a
Securities Purchase Agreement whereby Genencor International, Inc. ("Genencor")
will acquire capital stock of the Company (the "Stock Purchase");

        WHEREAS, the parties desire to amend the Agreement in the manner set
forth in this Amendment to provide that the Stock Purchase will not trigger the
issuance of Rights Certificates under the Agreement.

                                    AGREEMENT

        NOW, THEREFORE, in consideration of the benefits described in the
RECITALS hereto and the mutual promises hereinafter set forth, the parties
hereto agree as follows:

1.      Except as otherwise defined herein, capitalized terms used but not
        defined herein shall have the respective meanings given to them in the
        Agreement.

2.      Section 1(a) of the Agreement is hereby amended and restated in its
        entirety as follows:

           "(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 of the Company then outstanding,
           but shall not include the Company, any Subsidiary (as such term is
           hereinafter defined) of the Company, any employee benefit plan of the
           Company or any Subsidiary of the Company, or any entity holding
           Common Shares for or pursuant to the terms of any such plan.
           Notwithstanding the foregoing, no Person shall become an "Acquiring
           Person" 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 of the Common Shares of the Company then
           outstanding; provided, however, that if a Person shall become the
           Beneficial Owner of 15% or more of the Common Shares of the Company
           then outstanding by reason of share purchases by the


<PAGE>

           Company and shall, after such share purchases by the Company, become
           the Beneficial Owner of any additional Common Shares of the Company,
           then such Person shall be deemed to be an "Acquiring Person."
           Notwithstanding the foregoing, if the Incumbent Board of Directors of
           the Company (as hereinafter defined) determines in good faith that a
           Person who would otherwise be an "Acquiring Person," as defined
           pursuant to the foregoing provisions of this paragraph (a), has
           become such inadvertently, and such Person divests as promptly as
           practicable 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.

           In addition, G.D. Searle & Co., a Delaware corporation ("Searle"),
           shall not be deemed to be an "Acquiring Person" for purposes of this
           Agreement solely to the extent that Searle and any of its Affiliates
           or Associates (i) Beneficially Own the Company's capital stock as of
           the date hereof or (ii) acquire the Company's Common Shares in
           accordance with the terms of that certain Preferred Stock Exchange
           Agreement, dated July 1, 1999, between Searle and the Company or any
           documents executed in connection with or pursuant thereto, including,
           but not limited to, that certain Investor Rights Agreement, dated
           July 1, 1999, between Searle and the Company. Solely for the purposes
           of the foregoing, "Searle" shall include any entity which acquires
           all or substantially all of the business or assets of such entity.

           In addition, State of Wisconsin Investment Board ("SWIB"), shall not
           be deemed to be an "Acquiring Person" for purposes of this Agreement
           solely to the extent that SWIB and any of its Affiliates or
           Associates (i) Beneficially Own the Company's capital stock as of the
           date hereof or (ii) acquire the Company's Common Shares in accordance
           with the terms of that certain Common Stock Purchase Agreement, dated
           February 15, 2000, between SWIB and the Company or any documents
           executed in connection with or pursuant thereto. Solely for the
           purposes of the foregoing, "SWIB" shall include any entity which
           acquires all or substantially all of the business or assets of such
           entity.

           In addition, Genencor International, Inc., a Delaware corporation
           ("Genencor"), shall not be deemed to be an "Acquiring Person" for
           purposes of this Agreement solely to the extent that Genencor and any
           of its Affiliates or Associates (i) Beneficially Own the Company's
           capital stock as of July 9, 2001 or (ii) acquire the Company's Common
           Shares in accordance with the terms of that certain Securities
           Purchase Agreement, dated July 9, 2001 between Genencor and the
           Company or any documents executed in connection with or pursuant
           thereto. Solely for the purposes of the foregoing, "Genencor" shall
           include any entity which acquires all or substantially all of the
           business or assets of such entity."



<PAGE>

3.      This Amendment shall be governed by and construed in accordance with the
        laws of the State of California.

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



                      [THIS SPACE INTENTIONALLY LEFT BLANK]
<PAGE>
IN WITNESS WHEREOF, the parties have executed this Amendment on the day and year
first written above.

     EPIMMUNE INC.                            AMERICAN STOCK TRANSFER &
                                              TRUST COMPANY



By:  /s/ Robert J. De Vaere                   By:
     ---------------------------------------     ----------------------------
     Robert J. De Vaere                       Print Name:
     Vice President Finance and                          --------------------
        Chief Financial Officer               Title:
                                                    -------------------------
<PAGE>
                      FOURTH AMENDMENT TO RIGHTS AGREEMENT


        This FOURTH AMENDMENT (the "Amendment") to the Rights Agreement (the
"Agreement") entered into as of March 19, 1993, as amended June 29, 1999,
February 15, 2000, and July 9, 2001, by and between EPIMMUNE INC. (formerly
Cytel Corporation), a Delaware corporation (the "Company"), and AMERICAN STOCK
TRANSFER & TRUST COMPANY (the "Rights Agent"), is entered into as of December
18, 2001.

                                    RECITALS

        WHEREAS, concurrently herewith, the Company is entering into a Share
Purchase Agreement whereby State of Wisconsin Investment Board and Genencor
International, Inc. will acquire capital stock of the Company (the "Stock
Purchase");

        WHEREAS, the parties desire to amend the Agreement in the manner set
forth in this Amendment to provide that neither the State of Wisconsin
Investment Board or Genencor International, Inc. will be deemed an Acquiring
Person (as defined below) due to the Stock Purchase.

                                    AGREEMENT

        NOW, THEREFORE, in consideration of the benefits described in the
RECITALS hereto and the mutual promises hereinafter set forth, the parties
hereto agree as follows:

1.      Except as otherwise defined herein, capitalized terms used but not
        defined herein shall have the respective meanings given to them in the
        Agreement.

2.      Section 1(a) of the Agreement is hereby amended and restated in its
        entirety as follows:

           "(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 of the Company then outstanding,
           but shall not include the Company, any Subsidiary (as such term is
           hereinafter defined) of the Company, any employee benefit plan of the
           Company or any Subsidiary of the Company, or any entity holding
           Common Shares for or pursuant to the terms of any such plan.
           Notwithstanding the foregoing, no Person shall become an "Acquiring
           Person" 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 of the Common Shares of the Company then
           outstanding; provided, however, that if a Person shall become the
           Beneficial Owner of 15% or more of the Common Shares of the Company
           then outstanding by reason of share purchases by the Company and
           shall, after such share purchases by the


<PAGE>

           Company, become the Beneficial Owner of any additional Common Shares
           of the Company, then such Person shall be deemed to be an "Acquiring
           Person." Notwithstanding the foregoing, if the Incumbent Board of
           Directors of the Company (as hereinafter defined) determines in good
           faith that a Person who would otherwise be an "Acquiring Person," as
           defined pursuant to the foregoing provisions of this paragraph (a),
           has become such inadvertently, and such Person divests as promptly as
           practicable 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.

           In addition, G.D. Searle & Co., a Delaware corporation ("Searle"),
           shall not be deemed to be an "Acquiring Person" for purposes of this
           Agreement solely to the extent that Searle and any of its Affiliates
           or Associates (i) Beneficially Own the Company's capital stock as of
           the date hereof or (ii) acquire the Company's Common Shares in
           accordance with the terms of that certain Preferred Stock Exchange
           Agreement, dated July 1, 1999, between Searle and the Company or any
           documents executed in connection with or pursuant thereto, including,
           but not limited to, that certain Investor Rights Agreement, dated
           July 1, 1999, between Searle and the Company. Solely for the purposes
           of the foregoing, "Searle" shall include any entity which acquires
           all or substantially all of the business or assets of such entity.

           In addition, State of Wisconsin Investment Board ("SWIB"), shall not
           be deemed to be an "Acquiring Person" for purposes of this Agreement
           solely to the extent that SWIB and any of its Affiliates or
           Associates (i) Beneficially Own the Company's capital stock as of the
           date hereof; (ii) acquire the Company's Common Shares in accordance
           with the terms of that certain Common Stock Purchase Agreement, dated
           February 15, 2000, between SWIB and the Company or any documents
           executed in connection with or pursuant thereto; or (iii) acquire the
           Company's Common Shares in accordance with the terms of that certain
           Share Purchase Agreement dated December 14, 2001 between SWIB and the
           Company or any documents executed in connection or pursuant thereto.
           Solely for the purposes of the foregoing, "SWIB" shall include any
           entity which acquires all or substantially all of the business or
           assets of such entity.

           In addition, Genencor International, Inc., a Delaware corporation
           ("Genencor"), shall not be deemed to be an "Acquiring Person" for
           purposes of this Agreement solely to the extent that Genencor and any
           of its Affiliates or Associates (i) Beneficially Own the Company's
           capital stock as of July 9, 2001, (ii) acquire the Company's Common
           Shares in accordance with the terms of that certain Securities
           Purchase Agreement, dated July 9, 2001 between Genencor and the
           Company or any documents executed in connection


<PAGE>

           with or pursuant thereto; or (iii) acquire the Company's Common
           Shares in accordance with the terms of that certain Share Purchase
           Agreement dated December 14, 2001 between Genencor and the Company or
           any documents executed in connection or pursuant thereto. Solely for
           the purposes of the foregoing, "Genencor" shall include any entity
           which acquires all or substantially all of the business or assets of
           such entity."

3.      This Amendment shall be governed by and construed in accordance with the
        laws of the State of California.

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



                      [THIS SPACE INTENTIONALLY LEFT BLANK]

<PAGE>
IN WITNESS WHEREOF, the parties have executed this Amendment on the day and year
first written above.

     EPIMMUNE INC.                              AMERICAN STOCK TRANSFER &
                                                TRUST COMPANY



By:  /s/ Robert J. De Vaere                     By:
     ----------------------------------             ----------------------------
     Robert J. De Vaere
     Vice President Finance and                 Print Name:
           Chief Financial Officer                         ---------------------
                                                Title:
                                                      --------------------------