Management Stockholders Agreement

MANAGEMENT STOCKHOLDERS AGREEMENT


MANAGEMENT STOCKHOLDERS AGREEMENT dated as of August 22, 1997 among Cambrex Corporation, a Delaware corporation ("Parent"), BW Acquisition Corporation, a Delaware corporation ("Purchaser") and the parties listed on Schedule A attached hereto (each a "Stockholder" and, collectively, the "Stockholders").


WHEREAS, concurrently herewith Parent, the Purchaser, and BioWhittaker, Inc., a Delaware corporation (the "Company"), are entering into an Agreement and Plan of Merger of even date herewith (as such agreement may be amended from time to time, the "Merger Agreement"; capitalized terms used but not otherwise defined herein shall have the respective meanings ascribed to them in the Merger Agreement) pursuant to which the Purchaser will be merged with and into the Company (the "Merger"); and


WHEREAS, in furtherance thereof, the Parent proposes that the Purchaser make an offer (the "Offer") to purchase for cash all of the issued and outstanding shares of common stock of the Company, and all associated rights to purchase preferred stock, at a price of $11.625 per share net to the seller;


WHEREAS, Parent has required, as a condition to its entering into the Merger Agreement and commencing the Offer, that each Stockholder enter into, and each such Stockholder has agreed to enter into, this Agreement.


NOW, THEREFORE, to satisfy this condition and in consideration of Parent's entering into the Merger Agreement and causing the Offer to be commenced, respectively, and in consideration of the premises and the representations, warranties and covenants contained herein, the parties agree as follows:


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1. Representations and Warranties of Each Stockholder. Each Stockholder hereby severally as to itself represents and warrants to Parent as follows:


(a) Ownership of Shares and Stock Options. (i) Such
Stockholder (together, in the case of Mr. Buterbaugh, with Mr.
Buterbaugh's wife) is the record holder and beneficial owner of the
number of shares of the common stock of the Company, par value $.01 per
share (the "Company Common Stock"), set forth opposite such
Stockholder's name on Schedule A hereto (the "Existing Shares", and
together with any shares of Company Common Stock acquired by such
Stockholder after the date hereof and prior to the termination hereof,
whether upon exercise of options or warrants, conversion of convertible
securities, purchase, exchange or otherwise, the "Shares").


(ii) On the date hereof, the Existing Shares set forth
opposite such Stockholder's name on Schedule A constitute all of the
shares of Company Common Stock owned by such Stockholder.


(iii) Such Stockholder has (A) sole power of disposition; (B)
sole voting power; and (C) sole power to demand dissenter's or
appraisal rights, in each case with respect to all of such
Stockholder's Existing Shares and with no restrictions on such rights,
subject to applicable federal securities laws and the terms of this
Agreement.


(iv) Each Stockholder owns validly issued and outstanding
options (the "Stock Options") to acquire the number of shares of
Company Common Stock set forth opposite such Stockholder's name on
Schedule A hereto (all such shares underlying such Stockholder's Stock
Options being referred to herein collectively as the "Option Shares").
All such Stock Options are fully vested and freely exercisable by such
Stockholder to


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acquire any and all such Option Shares at any time at his option.


(b) Power; Binding Agreement. Such Stockholder has all
requisite legal capacity, power and authority to enter into and perform
all of such Stockholder's obligations under this Agreement. The
execution, delivery and performance of this Agreement by such
Stockholder will not violate any other agreement to which such
Stockholder is a party or by which such Stockholder is bound including,
without limitation, any voting agreement, stockholders agreement,
voting trust or other agreement. This Agreement has been duly and
validly authorized, executed and delivered by such Stockholder and
constitutes a valid and binding agreement of such Stockholder,
enforceable against such Stockholder in accordance with its terms,
except as such enforceability may be limited by bankruptcy, insolvency,
moratorium or other similar laws affecting or relating to the
enforcement of creditors' rights generally or by general principles of
equity. There is no beneficiary of or holder of a voting trust
certificate whose consent is required for the execution and delivery of
this Agreement or the consummation of the transactions contemplated
hereby. If such Stockholder is married and such Stockholder's Shares
constitute community property or otherwise require spousal or other
approval for this Agreement to be legal, valid and binding, this
Agreement has been duly authorized, executed and delivered by, and
constitutes a valid and binding agreement of, such Stockholder's
spouse, enforceable against such person in accordance with its terms,
except as such enforceability may be limited by bankruptcy, insolvency,
moratorium or other similar laws affecting or relating to the
enforcement of creditors' rights generally or by general principles of
equity.


(c) No Conflicts. Except for filing under the
Hart-Scott-Rodino Antitrust Improvements Act of 1976,


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as amended (the "HSR Act"), if applicable, (i) no filing with, and no
permit, authorization, consent or approval of, any state or federal
public body or authority is necessary for the execution of this
Agreement by such Stockholder and the consummation by such Stockholder
of the transactions contemplated hereby and (ii) neither the execution
and delivery of this Agreement by such Stockholder nor the consummation
by such Stockholder of the transactions contemplated hereby nor
compliance by such Stockholder with any of the provisions hereof shall
(A) conflict with or result in any breach of the applicable
organization documents applicable to such Stockholder, (B) result in a
material violation or breach of, or constitute (with or without notice
or lapse of time or both) a default (or give rise to any third party
right of termination, cancellation, modification, prepayment or
acceleration) under any of the terms, conditions or provisions of any
material note, bond, mortgage, indenture, license, contract,
commitment, arrangement, understanding, agreement or other instrument
or obligation of any kind to which such Stockholder is a party or by
which such Stockholder or any of such Stockholder's properties or
assets may be bound or (C) violate any order, writ, injunction, decree,
judgment, statute, rule, regulation or governmental permit or license
(collectively, "Laws") applicable to such Stockholder or any of such
Stockholder's properties or assets.


(d) Such Stockholder's Shares and the certificates
representing such Shares are now and at all times during the term
hereof will be held by such Stockholder, or by a nominee or custodian
for the benefit of such Stockholder, free and clear of all liens,
claims, security interests, proxies, voting trusts or agreements,
understandings, arrangements or any other encumbrances whatsoever,
except for any such encumbrances or proxies arising hereunder.


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(e) No broker, investment banker, financial adviser or other
Person is entitled to any broker's, finder's, financial adviser's or
other similar fee or commission in connection with the transactions
contemplated hereby based upon arrangements made by or on behalf of
such Stockholder.


(f) Such Stockholder understands and acknowledges that Parent
is entering into the Merger Agreement in reliance upon such
Stockholder's execution and delivery of this Agreement.


2. Agreement to Tender. Shares. Each Stockholder hereby irrevocably agrees to duly tender all of the Shares of such Stockholder pursuant to the terms of the Offer and not to withdraw such Shares prior to the expiration of the Offer.


3. Agreement to Vote; Proxy.


(a) Voting. Each Stockholder hereby severally as to itself agrees that, during the time this Agreement is in effect, at any meeting of the stockholders of the Company, however called, or in connection with any written consent of the stockholders of the Company, such Stockholder shall vote (or cause to be voted) the Shares of such Stockholder (i) in favor of the Merger, the execution and delivery by the Company of the Merger Agreement and the approval of the terms thereof and each of the other actions contemplated by the Merger Agreement and this Agreement and any actions required in furtherance hereof and thereof; (ii) against any action or agreement that would result in a breach of any covenant, representation or warranty or any other obligation or agreement of the Company under the Merger Agreement, the Offer or this Agreement; and (iii) except as specifically requested in writing by Parent in advance, against the following actions (other than the Merger and the transactions contemplated by the Merger Agreement): (A) any extraordinary corporate transaction, such as a merger, consolidation or other business combination involving the


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