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                            CIPHERGEN BIOSYSTEMS, INC

             FOURTH AMENDED AND RESTATED INVESTORS RIGHTS AGREEMENT




                                  MARCH 3, 2000

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                                TABLE OF CONTENTS

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                                                                                                                   PAGE
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SECTION 1 TERMINATION OF THE THIRD AMENDED AND RESTATED INVESTORS RIGHTS AGREEMENT....................................1

SECTION 2 RESTRICTIONS ON TRANSFER; REGISTRATION RIGHTS...............................................................2

         2.1      Restrictions on Transferability.....................................................................2
         2.2      Certain Definitions.................................................................................2
         2.3      Restrictive Legend..................................................................................3
         2.4      Notice of Proposed Transfer.........................................................................3
         2.5      Demand Registration Rights..........................................................................4
         2.6      Company Registration................................................................................6
         2.7      Form S-3 Registration Rights........................................................................7
         2.8      Expenses of Registration............................................................................8
         2.9      Registration Procedures.............................................................................8
         2.10     Indemnification.....................................................................................9
         2.11     Information by Holder..............................................................................11
         2.12     Rule 144 Reporting.................................................................................11
         2.13     Transfer of Registration Rights....................................................................12
         2.14     Termination of Registration Rights.................................................................12
         2.15     "Market Stand Off" Agreement.......................................................................13
         2.16     Inclusion of Common Stock Held by Founders.........................................................13
         2.17     Limitations on Subsequent Registration Rights......................................................13

SECTION 3 AFFIRMATIVE COVENANTS OF THE COMPANY.......................................................................13

         3.1      Financial Information..............................................................................13
         3.2      Inspection.........................................................................................14
         3.3      Assignment of Rights to Financial Information......................................................14
         3.4      Termination of Covenants...........................................................................14

SECTION 4 AFFIRMATIVE COVENANT OF INVESTORS; RIGHT OF FIRST REFUSAL..................................................15

         4.1      Confidential Information, etc......................................................................15
         4.2      Right of First Refusal.............................................................................15

SECTION 5 MISCELLANEOUS..............................................................................................16

         5.1      Governing Law......................................................................................16
         5.2      Successors and Assigns.............................................................................17
         5.3      Entire Agreement...................................................................................17
         5.4      Rights of Investors and Founders...................................................................17
         5.5      Notices, etc.......................................................................................17
         5.6      Counterparts.......................................................................................17
         5.7      Severability.......................................................................................17
         5.8      Approval of Amendments and Waivers.................................................................17
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                                       -i-
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                              CIPHERGEN BIOSYSTEMS

             FOURTH AMENDED AND RESTATED INVESTORS RIGHTS AGREEMENT

         THIS FOURTH AMENDED AND RESTATED INVESTORS RIGHTS AGREEMENT (the
"Agreement") is dated as of March 3, 2000 among CIPHERGEN BIOSYSTEMS, INC., a
California corporation (the "Company"), with its principal office located at
490 San Antonio Road, Suite #201, Palo Alto, CA 94306, the undersigned
holders of the Company's Series A Preferred Stock, Series B Preferred Stock,
Series C Preferred Stock, Series D Preferred Stock and Series E Preferred
Stock (collectively, the "Preferred Stock"), any individual or entity which
may hereafter become a party hereto pursuant to Section 5.8 of this Agreement
(each, individually, an "Investor" and collectively, the "Investors") and
Dean V. Ambrose, Edward O. Ansell, Steven M. Clark, Jonathan J. Kent and
Stephen B.H. Kent (each, individually, a "Founder" and Collectively, the
"Founders").

                                    RECITALS

         WHEREAS, the Company, and certain Investors and the Founders have
entered into that certain Third Amended and Restated Investors Right
Agreement, dated as of September 30, 1998, as amended (the "Third Amended
Investors Rights Agreement"), which superseded the Second Amended Investors
rights Agreement; and

         WHEREAS, the Company and certain Investors are entering into that
certain Series E Stock Purchase Agreement (the "Series E Agreement") of even
date herewith; and

         WHEREAS, as a condition of the closing of the financing provided for
in the Series E Agreement, and as an inducement to the additional financing
of the Company provided for therein, the Company and the Investors desire to
amend and restate in full the various covenants and restrictions set forth in
the Third Amended Investors Rights Agreement, in the form set forth herein;

         NOW, THEREFORE, in consideration of the mutual agreements, covenants
and conditions contained herein, the parties hereby agree as follows:

                                    SECTION 1

                      TERMINATION OF THE THIRD AMENDED AND
                       RESTATED INVESTORS RIGHTS AGREEMENT

         1.1 The parties hereto agree that, upon execution of this Agreement
by the Company and Investors holding at least a majority of the currently
outstanding shares of Registrable Securities (as the terms "Investors" and
"Registrable Securities" are defined in the Third Amended Investor Rights
Agreement), the Third Amended Investors Rights Agreement shall be terminated
with no further force or effect, and that this Agreement shall define the
rights and obligations of the parties hereto on

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the subject matter hereof with respect to shares of Common Stock of the
Company (the "Common Stock") and Preferred Stock held by the Investors and
Founders.

                                    SECTION 2

                  RESTRICTIONS ON TRANSFER; REGISTRATION RIGHTS

         2.1 RESTRICTIONS ON TRANSFERABILITY. The Preferred Stock (and any
Common Stock into which the Preferred Stock may be converted) shall not be
transferable except upon the conditions specified in this Agreement, which
conditions are intended to insure compliance with the provisions of the
Securities Act (as hereinafter defined), or upon such other terms as are in
the opinion of counsel to the Company satisfactory to comply with the
provisions of the Securities Act. Except for transfers made pursuant to Rule
144 of the Securities Act, each Holder (as hereinafter defined) will cause
any proposed transferee of Preferred Stock (and any Common Stock into which
the Preferred Stock may be converted) held by such Holder to agree to take
and hold such securities subject to the provisions and upon the conditions
specified in this Agreement and it will be a condition precedent to the
effectiveness of any such transfer that the Company shall have secured a
written agreement in form and substance satisfactory to the Company to that
effect, if so requested by the Company.

         2.2 CERTAIN DEFINITIONS. As used in this Agreement, the following
terms shall have the following respective meanings:

         "COMMISSION" shall mean the Securities and Exchange Commission or
any other federal agency at the time administering the Securities Act.

         "FORM S-3" shall mean Form S-3 under the Securities Act as in effect
on the date of this Agreement, or any substantially similar, equivalent or
successor form under the Securities Act.

         "FOUNDERS' ORIGINAL COMMON STOCK" shall mean that Common Stock
listed on SCHEDULE A attached hereto.

         "HOLDER" shall mean any Investor or Founder, or any transferee of
registration rights under Section 2.13 hereof, who then holds any outstanding
Preferred Stock or Registrable Securities.

         "INVESTORS' ORIGINAL COMMON STOCK" shall mean that Common Stock
listed on SCHEDULE B attached hereto.

         "REGISTER," "REGISTERED" AND "REGISTRATION" refer to a registration
effected by preparing and filing a registration statement in compliance with
the Securities Act, and the declaration or ordering of the effectiveness of
such registration statement.

         "REGISTRABLE SECURITIES" shall mean (i) shares of the Common Stock
issued or issuable upon the conversion of the Preferred Stock which have not
been sold to the public, (ii) shares of the Investors' Original Common Stock
which have not been sold to the public, (iii) shares of the Common Stock
issued upon any stock split, stock dividend, recapitalization, or similar
event, which

                                       -2-
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have not been sold to the public, in respect of (a) shares of the Preferred
Stock, (b) shares of Common Stock issued or issuable upon the conversion of
the Preferred Stock or (c) shares of Investors' Original Common Stock and
(iv) shares of Founders' Original Common Stock which have not been sold to
the public and are included as Registrable Securities pursuant to Section
2.16, solely for the purposes set forth therein.

         "REGISTRATION EXPENSES" shall mean all expenses incurred in
complying with Sections 2.5, 2.6 and 2.7 hereof, including, without
limitation, all registration, qualification and filing fees, printing
expenses, escrow fees, fees and disbursements of counsel for the Company,
blue sky fees and expenses, and the expense of any special audits incident to
or required by any such registration (but excluding the compensation of
regular employees of the Company which shall be paid in any event by the
Company).

         "RESTRICTED SECURITIES" shall mean the securities of the Company
required to bear the legend set forth in Section 2.3 hereof or a legend
substantially similar thereto and all shares of Founders' Original Common
Stock and Investors' Original Common Stock.

         "SECURITIES ACT" shall mean the Securities Act of 1933, as amended,
or any similar federal statute and the rules and regulations of the
Commission thereunder, all as the same shall be in effect at the time.

         "SELLING EXPENSES" shall mean all underwriting discounts and selling
commissions applicable to the applicable sale.

         2.3 RESTRICTIVE LEGEND. Each certificate representing (i) the
Preferred Stock, (ii) shares of the Common Stock issued upon conversion of
the Preferred Stock or upon any stock split, stock dividend,
recapitalization, merger, consolidation or similar event, shall (unless
otherwise permitted by the provisions of Section 2.4 below) be stamped or
otherwise imprinted with a legend in the following form (in addition to any
legend required under applicable California or other state securities laws):

         THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE BEEN ACQUIRED FOR
         INVESTMENT AND HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF
         1933. SUCH SHARES MAY NOT BE SOLD OR TRANSFERRED IN THE ABSENCE OF SUCH
         REGISTRATION OR AN EXEMPTION THEREFROM UNDER SAID ACT. COPIES OF THE
         AGREEMENT COVERING THE PURCHASE OF THESE SHARES AND RESTRICTING THEIR
         TRANSFER MAY BE OBTAINED AT NO COST BY WRITTEN REQUEST MADE BY THE
         HOLDER OF RECORD OF THIS CERTIFICATE TO THE SECRETARY OF THE
         CORPORATION.

         2.4 NOTICE OF PROPOSED TRANSFER. The holder of each certificate
representing Restricted Securities, by acceptance thereof, agrees to comply
in all respects with the provisions of this Section 2.4. Prior to any
proposed transfer of any Restricted Securities, unless there is in effect a
registration statement under the Securities Act covering the proposed
transfer, the holder thereof shall give written notice to the Company of such
holder's intention to effect such transfer. Each such notice

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shall describe the manner and circumstances of the proposed transfer in
sufficient detail, and shall be accompanied (except in transactions in
compliance with Rule 144) by either (i) a written opinion of legal counsel
who shall be reasonably satisfactory to the Company addressed to the Company
and reasonably satisfactory in form and substance to the Company's counsel,
to the effect that the proposed transfer of the Restricted Securities may be
effected without registration under the Securities Act, or (ii) (x) a "no
action letter" from the Commission to the effect that the transfer of such
securities without registration will not result in a recommendation by such
staff that action be taken with respect thereto and (y) a copy of such
holder's request (together with all supplements or amendments thereto) for
such letter which shall have been provided to the Company at or prior to the
time of first delivery to the Commission's staff, whereupon the holder of
such Restricted Securities shall be entitled to transfer such Restricted
Securities in accordance with the terms of the notice delivered by the holder
to the Company. Each certificate evidencing the Restricted Securities
transferred as provided for above shall bear the appropriate restrictive
legend set forth in Section 2.3 above, except that such certificate shall not
bear such restrictive legend if, in the opinion of counsel for the Company or
counsel for such holder, which opinion and counsel shall be satisfactory to
counsel for the Company, such legend is not required in order to establish
compliance with any provisions of the Securities Act.

         Notwithstanding the provisions above, no such opinion of counsel or
"no action letter" shall be necessary for a transfer by an Investor (i) which
is a partnership to a partner of such partnership or a retired partner of
such partnership who retires after the date hereof, or to the estate of any
such partner or retired partner or the transfer by gift, will or intestate
succession of any partner to his or her spouse or to the siblings, lineal
descendants or ancestors of such partner or his or her spouse, or (ii) to an
affiliate of an Investor if, in each case, the transferee agrees in writing
to be subject to the terms hereof to the same extent as if he or she were an
original Investor hereunder.

         2.5 DEMAND REGISTRATION RIGHTS.

                  (a) Commencing on the earlier of (i) six months after the
effective date of the first registration statement filed by the Company
covering an underwritten offering of any of its securities to the general
public and (ii) February ___, 2004, if the Company shall receive a written
request (specifying that it is being made pursuant to this Section 2.5) from
Holders of more than fifty percent (50%) of the outstanding Registrable
Securities then held by all Holders (the "Initiating Holders") that the
Company file a registration statement or similar document under the
Securities Act covering the registration of at least fifty percent (50%) of
the then outstanding Registrable Securities or any lesser percentage if the
anticipated aggregate offering proceeds, net of underwriting discounts and
commissions would exceed $5,000,000, then the Company shall promptly notify
all other Holders of such request and shall use its best efforts to cause all
Registrable Securities that such Holders have requested, within 15 days after
receipt of such written notice, be registered in accordance with this Section
2.5 to be registered under the Securities Act.

         Notwithstanding the foregoing, (i) the Company shall not be
obligated to effect a registration pursuant to this Section 2.5 during the
period starting with the date sixty (60) days prior to the Company's
estimated date of filing of, and ending on a date sixty (60) days following
the effective

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date of, a registration statement pertaining to an underwritten public
offering of the Company's securities, provided that the Company is actively
employing in good faith all reasonable efforts to cause such registration
statement to become effective and that the Company's estimate of the date of
filing such registration statement is made in good faith and (ii) if the
Company shall furnish to such Holders a certificate signed by the President
of the Company stating that in the good faith judgment of the Board of
Directors it would be seriously detrimental to the Company or its
shareholders for a registration statement to be filed in the near future,
then the Company's obligation to use its best efforts to file a registration
statement shall be deferred for a period not to exceed one hundred twenty
(120) days; provided, however, that the Company shall not obtain such a
deferral more than once in any twelve (12) month period.

         The Company shall be obligated to effect not more than two
registrations pursuant to this Section 2.5; PROVIDED, HOWEVER, that such
obligation shall be deemed satisfied only when a registration statement
covering at least fifty-one percent (51%) of the Registrable Securities
requested to be registered shall have become effective, and if the method of
disposition is an underwritten offering, all such shares have been sold
pursuant thereto.

                  (b) If the Initiating Holders intend to distribute the
Registrable Securities covered by their demand by means of an underwriting,
they shall so advise the Company as part of their demand made pursuant to
this Section 2.5, and the Company shall include such information in the
notice referred to in Section 2.5(a). In such event, the right of any Holder
to registration pursuant to this Section 2.5 shall be conditioned upon such
Holder's participation in such underwriting and the inclusion of such
Holder's Registrable Securities in the underwriting (unless otherwise
mutually agreed by a majority in interest of the Initiating Holders and such
Holder) to the extent provided herein.

         The Company shall, together with all Holders proposing to distribute
their securities through such underwriting, enter into an underwriting
agreement in customary form with the underwriter or underwriters selected by
a majority of interest of the Initiating Holders and reasonably satisfactory
to the Company. Notwithstanding any other provision of this Section 2.5, if
the underwriter shall advise the Company in writing that marketing factors
(including, without limitation, an adverse effect on the per share offering
price) require a limitation of the number of shares to be underwritten, then
the Company shall so advise all Holders of Registrable Securities that would
otherwise be registered and underwritten pursuant hereto, and the number of
shares of Registrable Securities that may be included in the registration and
underwriting shall be allocated pro rata among such Holders thereof in
proportion, as nearly as practicable, to the respective amounts of
Registrable Securities held by such Holders at the time of filing the
registration statement. No Registrable Securities excluded from the
underwriting by reason of the foregoing underwriter's marketing limitation
shall be included in such registration.

         If any Holder disapproves of the terms of the underwriting, such
Holder may elect to withdraw therefrom by written notice to the Company, the
underwriter, and the Initiating Holders. The Registrable Securities so
withdrawn shall also be withdrawn from registration. If by the withdrawal of
such Registrable Securities a greater number of Registrable Securities held
by other

                                       -5-
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Holders may be included in such registration (up to the maximum of any
limitation imposed by the underwriters), then the Company shall offer to all
Holders who have included Registrable Securities in the registration the
right to include additional Registrable Securities in the same proportion
used in determining the underwriter limitation in this Section 2.5.

         If the underwriter has not limited the number of Registrable
Securities to be underwritten, the Company may include securities for its own
account (or for the account of other shareholders) in such registration if
the underwriter so agrees and if the number of Registrable Securities that
would otherwise have been included in such registration and underwriting will
not thereby be limited.

         Except for registration statements on Form S-4, S-8 or any successor
thereto, the Company will not file with the Commission without the approval
of the Initiating Holders any other new registration statements with respect
to its capital stock, whether for its own account or that of other
shareholders, from the date of receipt of a notice from the Initiating
Holders until the earlier of (i) 180 days from the date of receipt of such
notice and (ii) the completion of the period of distribution of the
registration contemplated thereby.

         2.6 COMPANY REGISTRATION.

                  (a) If, at any time or from time to time, the Company shall
determine to register any of its securities, either for its own account or
the account of a security holder or holders exercising their respective
demand registration rights, other than a registration relating solely to
employee benefit plans on Form S-8 or similar forms which may be promulgated
in the future or a registration on Form S-4 or similar forms which may be
promulgated in the future relating solely to a Securities and Exchange
Commission Rule 145 or similar transaction, the Company will (i) promptly
give to each Holder written notice thereof and (ii) include in such
registration (and any related qualification under blue sky laws or other
compliance), and in any underwriting involved therein, all Registrable
Securities of such Holders as specified in a written request or requests made
within 15 days after receipt of such written notice from the Company.

                  (b) UNDERWRITING. If the registration of which the Company
gives notice is for a registered public offering involving an underwriting,
the Company shall so indicate in the notice given pursuant to Section 2.6(a).
In such event the right of any Holder to registration pursuant to this
Section 2.6 shall be conditioned upon such Holder's agreeing to participate
in such underwriting and in the inclusion of such Holder's Registrable
Securities in the underwriting to the extent provided herein. All Holders
proposing to distribute their securities through such underwriting shall
(together with the Company and the other holders distributing their
securities through such underwriting) enter into an underwriting agreement in
customary form with the underwriter or underwriters selected for such
underwriting by the Company or by other holders exercising any demand
registration rights. Notwithstanding any other provision of this Section 2.6,
if the underwriter determines that marketing factors require a limitation of
the number of shares to be underwritten, the underwriter may exclude some or
all Registrable Securities or other securities from such registration and
underwriting (hereinafter an "Underwriter Cutback"). In the event of an
Underwriter Cutback, the Company shall so advise all Holders and the other
holders distributing their securities through such underwriting, and the
number of Registrable Securities that may be

                                       -6-
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included in the registration and underwriting shall be allocated among the
Holders in proportion, as nearly as practicable, to the respective amounts of
Registrable Securities held by such Holders at the time of filing the
registration statement. If any Holder disapproves of the terms of any such
underwriting, such Holder may elect to withdraw therefrom by written notice
to the Company and the underwriter. Any securities excluded or withdrawn from
such underwriting shall be withdrawn from such registration.

         2.7 FORM S-3 REGISTRATION RIGHTS. After the Company's initial
registered underwritten public offering, the Company shall use its best
efforts to qualify for registration on Form S-3, and to that end the Company
shall use its best efforts to comply with the reporting requirements of the
Securities Exchange Act of 1934, as amended (the "Securities Exchange Act"),
within twelve (12) months following the effective date of the first
registration of any securities of the Company for an underwritten registered
public offering. After the Company has qualified for the use of Form S-3, and
subject to the provisions of Section 2.14, each Holder shall have the right
to request registrations on Form S-3 (such requests shall be in writing and
shall state the number of shares of Registrable Securities to be disposed of
and the intended method of disposition of such shares by each such Holder),
subject only to the following limitations:

                  (a) The Company shall not be obligated to cause a
registration on Form S-3 to become effective prior to one hundred eighty
(180) days following the effective date of a Company initiated registration
(other than a registration effected solely to qualify an employee benefit
plan or to effect a business combination pursuant to Rule 145);

                  (b) The Company shall not be required to effect a
registration pursuant to this Section 2.7 unless the Holder or Holders
requesting such a registration propose to dispose of shares of Registrable
Securities having an aggregate disposition price (before deduction of
underwriting discounts and expenses of sale) of at least $1,000,000;

                  (c) The Company shall not be required to effect a
registration pursuant to this Section 2.7 if the Company shall furnish to the
requesting Holders a certificate signed by the President of the Company
stating that in the good faith judgment of the Board of Directors of the
Company it would be seriously detrimental to the Company or its shareholders
for the registration statement to be filed at the date filing would be
required, in which case the Company shall have an additional period of not
more than one hundred twenty (120) days within which to file such
registration statement; provided however, that the Company shall not use this
right more than once in any twelve (12) month period;

                  (d) The Company shall not be required to maintain and keep
any such registration on Form S-3 effective for a period exceeding one
hundred and twenty (120) days from the effective date thereof; and

                  (e) The Company shall not be obligated to cause a
registration on Form S-3 if in the prior twelve-month period the Company has
caused a registration on Form S-3 to become effective pursuant to this
Section 2.7.

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         The Company shall give notice to all Holders of the receipt of a
request for registration pursuant to this Section 2.7 and shall use its best
efforts to cause all Registrable Securities that such Holders have requested,
within 15 days after receipt of such written notice, be registered in
accordance with this Section 2.7 to be registered under the Securities Act.
Subject to the foregoing, the Company will use its best efforts to effect
promptly any registration pursuant to this Section 2.7. The provisions of
Section 2.5(b) shall apply to any registration effected pursuant to this
Section 2.7

         2.8 EXPENSES OF REGISTRATION. All Registration Expenses incurred in
connection with any registration, qualification or compliance pursuant to
Sections 2.5, 2.6 and 2.7 (exclusive of Selling Expenses but inclusive of the
reasonable fees and expenses of one special counsel to the selling Holders)
shall be borne by the Company. Notwithstanding anything to the contrary
herein, the Company shall not be required to pay for any expenses of any
registration proceeding under Section 2.5 if the registration request is
subsequently withdrawn at the request of the Holders of a majority of the
Registrable Securities to have been registered, unless such Holders agree to
forfeit their right to a demand registration pursuant to Section 2.5 (in
which event such right shall be forfeited by all Holders). In the absence of
such an agreement to forfeit, the Holders of Registrable Securities to have
been registered shall bear all such expenses pro rata on the basis of the
Registrable Securities to have been registered. Notwithstanding the
foregoing, however, if at the time of the withdrawal, the Holders have
learned of a material adverse change in the condition, business, or prospects
of the Company from that known to the Holders at the time of their request,
of which the Company had knowledge at the time of the request, then the
Holders shall not be required to pay any of said expenses and shall retain
their rights pursuant to Section 2.5.

         2.9 REGISTRATION PROCEDURES. In the case of each registration,
qualification or compliance effected by the Company pursuant to this Section
2, the Company will keep each Holder advised in writing as to the initiation
of each registration, qualification and compliance and as to the completion
thereof. At its expense the Company will:

                  (a) Keep such registration, qualification or compliance
effective for a period of one hundred twenty (120) days or until the Holder
or Holders have completed the distribution described in the registration
statement relating thereto, whichever first occurs;

                  (b) Prepare and file with the Commission such amendments
and supplements to such registration statement and the prospectus used in
connection with such registration statement as may be necessary to comply
with the provisions of the Securities Act with respect to the disposition of
all securities covered by such registration statement;

                  (c) Furnish to the Holders such numbers of copies of a
prospectus, including a preliminary prospectus, in conformity with the
requirements of the Securities Act, and such other documents as they may
reasonably request in order to facilitate the disposition of Registrable
Securities owned by them;

                  (d) Use its best efforts to register and qualify the
securities covered by such registration statement under such other securities
or blue sky laws of such jurisdictions as shall be reasonably requested by
the Holders, provided that the Company shall not be required in connection

                                       -8-
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therewith or as a condition thereto to qualify to do business or to file a
general consent to service of process in any such states or jurisdictions;

                  (e) In the event of any underwritten public offering, enter
into and perform its obligations under an underwriting agreement, in usual
and customary form, with the managing underwriter of such offering including,
without limitation causing to be furnished to the Initiating Holders (i) a
"cold comfort" letter of the Company's independent accountants as of the
effective date of the registration statement as to such matters as
customarily are covered in accountant's letters delivered to underwriters in
underwritten public offerings and (ii) an opinion of counsel to the Company,
as of the date of the closing of such underwritten public offering, in the
form customarily provided by issuer's counsel in underwritten public
offerings of securities. Each Holder participating in such underwriting shall
also enter into and perform its obligations under such an agreement; and

                  (f) Notify each Holder of Registrable Securities covered by
such registration statement at any time when a prospectus relating thereto is
required to be delivered under the Securities Act of any stop order,
injunction or other order or requirement of the Commission or any other
governmental agency or court that is issued which suspends the effectiveness
of the registration statement or of the happening of any event as a result of
which the prospectus included in such registration statement, as then in
effect, includes an untrue statement of a material fact or omits to state a
material fact required to be stated therein or necessary to make the
statements therein not misleading in the light of the circumstances then
existing.

         Notwithstanding any provision to the contrary in this Agreement, the
Company shall not be required in connection with any registration pursuant to
Sections 2.5, 2.6 or 2.7 to qualify shares in any state or jurisdiction which
requires the Company to qualify to do business or to file a general consent
to service of process.

         2.10 INDEMNIFICATION.

                  (a) The Company will indemnify each Holder, each of its
officers and directors and partners, and each person controlling such Holder
within the meaning of Section 15 of the Securities Act, with respect to which
registration, qualification or compliance has been effected pursuant to this
Section 2, and each underwriter, if any, and each person who controls any
underwriter within the meaning of Section 15 of the Securities Act, against
all expenses, claims, losses, damages and liabilities (or actions in respect
thereof), including any of the foregoing incurred in settlement of any
litigation, commenced or threatened, arising out of or based on any untrue
statement (or alleged untrue statement) of a material fact contained in any
registration statement, prospectus, offering circular or other document, or
any amendment or supplement thereto, incident to any such registration,
qualification or compliance, or based on any omission (or alleged omission)
to state therein a material fact required to be stated therein or necessary
to make the statements therein, in light of the circumstances in which they
were made, not misleading, or any violation by the Company of any rule or
regulation promulgated under the Securities Act applicable to the Company and
relating to action or inaction required of the Company in connection with any
such registration, qualification or compliance, and will reimburse each such
Holder, each of its officers


                                      -9-

<PAGE>

and directors and partners, and each person controlling such Holder, each
such underwriter and each person who controls any such underwriter, for any
legal and any other expenses reasonably incurred in connection with
investigating, preparing or defending any such claim, loss, damage, liability
or action, provided that the Company will not be liable in any such case to
the extent that any such claim, loss, damage, liability or expense arises out
of or is based on any untrue statement or omission or alleged untrue
statement or omission, made in reliance upon and in conformity with written
information furnished to the Company by an instrument duly executed by such
Holder or underwriter and stated to be specifically for use therein.

                  (b) Each Holder will, if Registrable Securities held by
such Holder are included in the securities as to which such registration,
qualification or compliance is being effected, indemnify the Company, each of
its directors and officers, each underwriter, if any, of the Company's
securities covered by such a registration statement, each person who controls
the Company or such underwriter within the meaning of Section 15 of the
Securities Act, and each other such Holder, each of its officers and
directors and partners and each person controlling such Holder within the
meaning of Section 15 of the Securities Act, against all expenses, claims,
losses, damages and liabilities (or actions in respect thereof) including any
of the foregoing incurred in settlement of any litigation commenced or
threatened, arising out of or based on any untrue statement (or alleged
untrue statement) of a material fact contained in any such registration
statement, prospectus, offering circular or other document, or any amendment
or supplement thereto, incident to any such registration, qualification or
compliance or based on any omission (or alleged omission) to state therein a
material fact required to be stated therein or necessary to make the
statements therein, in the light of the circumstances in which they were
made, not misleading, or any violation by the Company of any rule or
regulation promulgated under the Securities Act applicable to the Company in
connection with any such registration, qualification, or compliance, and will
reimburse the Company, such Holders, such directors, officers, partners,
persons, underwriters or control persons for any legal or any other expenses
reasonably incurred in connection with investigation, preparing or defending
any such claim, loss, damage, liability or action, in each case to the
extent, but only to the extent, that such untrue statement (or alleged untrue
statement) or omission (or alleged omission) is made in such registration
statement, prospectus, offering circular or other document or any amendment
or supplement thereto in reliance upon and in conformity with written
information furnished to the Company by an instrument duly executed by such
Holder and stated to be specifically for use therein; provided, however, that
the obligations of such Holders hereunder shall be limited to an amount equal
to the proceeds to each such Holder of Registrable Securities sold as
contemplated herein. The liability of a Holder hereunder shall be several and
not joint.

                  (c) Each party entitled to indemnification under this
Section 2.10 (the "Indemnified Party") shall give notice to the party
required to provide indemnification (the "Indemnifying Party") promptly after
such Indemnified Party has actual knowledge of any claim as to which
indemnity may be sought, and shall permit the Indemnifying Party to assume
the defense of any such claim or any litigation resulting therefrom, provided
that counsel for the Indemnifying Party, who shall conduct the defense of
such claim or litigation, shall be approved by the Indemnified Party (whose
approval shall not be unreasonably withheld), and the Indemnified Party may
participate in such defense at its own expense; provided, however, that an
Indemnified Party


                                      -10-

<PAGE>

(together with all other indemnified parties which may be represented without
conflict by one counsel) shall have the right to retain one separate counsel,
with the fees and expenses to be paid by the Indemnifying Party, if
representation of such Indemnified Party by the counsel retained by the
Indemnifying Party would be inappropriate due to actual or potential
conflicts of interests between such Indemnified Party and any other party
represented by such counsel in such proceeding. The failure of any
Indemnified Party to give notice as provided herein shall not relieve the
Indemnifying Party of its obligations under this Section 2 unless such
failure resulted in actual detriment to the Indemnifying Party. No
Indemnifying Party, in the defense of any such claim or litigation, shall,
except with the consent of each Indemnified Party, consent to entry of any
judgment or enter into any settlement which does not include as an
unconditional term thereof the giving by the claimant or plaintiff to such
Indemnified Party a release from all liability in respect of such claim or
litigation.

                  (d) If the indemnification provided for in this Section
2.10 is held by a court of competent jurisdiction to be unavailable to an
Indemnified Party with respect to any loss, liability, claim, damage, or
expense referred to therein, then the Indemnifying Party, in lieu of
indemnifying such Indemnified Party hereunder, shall contribute to the amount
paid or payable by such Indemnified Party as a result of such loss,
liability, claim, damage, or expense in such proportion as is appropriate to
reflect the relative fault of the Indemnifying Party on the one hand and of
the Indemnified Party on the other in connection with the statements or
omissions that resulted in such loss, liability, claim, damage, or expense as
well as any other relevant equitable considerations. The relative fault of
the Indemnifying Party and of the Indemnified Party shall be determined by
reference to, among other things, whether the untrue or alleged untrue
statement of a material fact or the omission to state a material fact relates
to information supplied by the Indemnifying Party or by the Indemnified Party
and the parties relative intent, knowledge, access to information, and
opportunity to correct or prevent such statement or omission.

                  (e) The obligations of the Company and Holders under this
Section 2.10 shall survive the completion of any offering of Registrable
Securities in a registration statement under this Section 2, and otherwise.

         2.11 INFORMATION BY HOLDER. The Holder or Holders of Registrable
Securities included in any registration shall furnish to the Company such
information regarding such Holder or Holders and the distribution proposed by
such Holder or Holders as the Company may request in writing and as shall be
required in connection with any registration, qualification or compliance
referred to in this Section 2.

         2.12 RULE 144 REPORTING. With a view to making available the
benefits of certain rules and regulations of the Commission which may at any
time permit the sale of the Restricted Securities to the public without
registration, after such time as a public market exists for the Common Stock
of the Company, the Company agrees to:

                  (a) Use its best efforts to make and keep public
information available, as those terms are understood and defined in Rule 144
under the Securities Act at all times after the effective date of the first
registration under the Securities Act filed by the Company for an offering of
its securities to the general public;


                                      -11-

<PAGE>

                  (b) Use its best efforts to then file with the Commission
in a timely manner all reports and other documents required of the Company
under the Securities Exchange Act at any time after it has become subject to
such reporting requirements;

                  (c) So long as a Holder owns any Restricted Securities, to
furnish to such Holder forthwith upon request a written statement by the
Company as to its compliance with the reporting requirements of said Rule 144
(at any time after 90 days after the effective date of the first registration
statement filed by the Company for an offering of its securities to the
general public) and of the Securities Act and the Securities Exchange Act (at
any time after it has become subject to such reporting requirements), a copy
of the most recent annual or quarterly report of the Company, and such other
reports and documents of the Company as a Holder may reasonably request in
availing itself of any rule or regulation of the Commission allowing a Holder
to sell any such securities without registration.

         2.13 TRANSFER OF REGISTRATION RIGHTS. The rights to cause the
Company to register securities granted under Sections 2.5, 2.6 and 2.7 may be
assigned or otherwise conveyed to a transferee or assignee of Registrable
Securities, who shall be considered a "Holder" for purposes of this Section
2, provided that (a) such transfer is effected in accordance with applicable
federal and state securities laws, (b) the Company is given written notice by
such Holder at the time of or within a reasonable time after said transfer,
stating the name, address and a reasonably detailed description of the
principal business or occupation of said transferee or assignee and any such
other information as is reasonably requested by the Company in order to carry
out the intent of these provisions and identifying the securities with
respect to which such registration rights are being assigned, (c) the Company
reasonably determines that the proposed transferee or assignee is not a
direct competitor or future competitor of the Company and (d) such transferee
or assignee (i) is a Holder, (ii) is an affiliate of a Holder, including a
wholly-owned subsidiary or constituent partner (including limited partners
and partners who retire from a transferor partnership after the date hereof)
of the transferring Holder, (iii) is a family member of the transferring
Holder, (iv) is a trust for the benefit of an individual transferor or his
family members, or (v) acquires at least 50,000 shares (as presently
constituted) of the Registrable Securities held by the transferring Holder.
No such transfer or assignment shall be valid or effective unless the
proposed transferee or assignee expressly agrees to be subject to all of the
provisions of this Agreement relating to such rights, including without
limitation the provisions of Sections 2.10 and 2.15 of this Agreement.

         2.14 TERMINATION OF REGISTRATION RIGHTS. The registration rights
granted pursuant to this Section 2 shall terminate as to any Holder upon the
earlier of (i) the sixth anniversary of the effective date of the first
registration statement filed by the Company covering an underwritten offering
of its securities to the general public at an aggregate offering price of not
less than $10,000,000 and at a public offering price equal to or exceeding
$5.50 per share (as adjusted for any stock dividends, combinations, or splits
with respect to such shares) and (ii) the date such Holder is able to
immediately sell all Registrable Securities held or entitled to be held upon
conversion by such Holder under Rule 144 during any 90-day period.


                                      -12-

<PAGE>

         2.15 "MARKET STAND OFF" AGREEMENT. Each Holder hereby agrees that it
shall not, to the extent requested by the Company and an underwriter of
Common Stock (or other securities) of the Company, sell or otherwise transfer
or dispose (other than to those who agree to be similarly bound) of any
Registrable Securities or any other securities of the Company for a period of
up to one hundred and eighty (180) days following the effective date of a
registration statement of the Company filed under the Securities Act;
provided, however, that (i) such agreement shall only be applicable to the
first such registration statement of the Company which covers shares (or
securities) to be sold on its behalf to the public in an underwritten
offering and (ii) all officers and directors of the Company enter into
similar agreements.

         In order to enforce the foregoing covenant, the Company may impose
stop-transfer instructions with respect to the Registrable Securities and
Common Stock of each Holder (and the shares or securities of every other
person subject to the foregoing restriction) until the end of such one
hundred eighty (180) day period.

         2.16 INCLUSION OF COMMON STOCK HELD BY FOUNDERS. In connection with
any registration effected pursuant to Section 2.6 hereof, each of the
Founders, with respect to all Founders' Original Common Stock, shall be
entitled to participate in such registration, on the same terms and
conditions as Holders selling their Registrable Securities in such
registration and, solely for purposes of Section 2.6, (i) each such Founder
shall be entitled to all of the rights and shall be subject to all of the
obligations applicable to a Holder in connection with such registration,
including without limitation the provisions of Sections 2.10 and 2.15 of this
Agreement, (ii) all such securities, and any shares of Common Stock issued in
respect thereof upon any stock split, stock dividend, recapitalization or
similar event, which have not been sold to the public, shall be deemed to be
"Registrable Securities," (iii) all references to "Holder" in this Agreement
shall be deemed to include such Founder for purposes of such registration and
(iv) any Underwriter Cutback shall apply pro rata to the shares so included
by the Founders participating in such registration.

         2.17 LIMITATIONS ON SUBSEQUENT REGISTRATION RIGHTS. From and after
the date of this Agreement, the Company shall not, without the prior written
consent of Holders holding more than fifty percent (50%) of the Registrable
Securities, enter into any agreement with any holder or prospective holder of
any securities of the Company which would allow such holder or prospective
holder to (i) require the Company to effect a registration or (ii) include
any securities in any registration filed under Sections 2.5, 2.6 or 2.7
hereof unless, under the terms of such agreement, such holder or prospective
holder may include such securities in any such registration only to the
extent that the inclusion of such securities will not diminish the amount of
Registrable Securities which are included in such registration, and such
agreement includes the equivalent of Section 2.15 as a term.

                                    SECTION 3

                      AFFIRMATIVE COVENANTS OF THE COMPANY

         3.1 FINANCIAL INFORMATION. The Company will furnish the following
reports to each Investor for so long as such Investor is a holder of (or is
entitled to purchase under this Agreement)


                                      -13-

<PAGE>

at least 100,000 shares of Preferred Stock or Common Stock issued upon
conversion of the Preferred Stock or a combination thereof:

                  (a) As soon as practicable after the end of each fiscal
year, and in any event within 90 days thereafter, audited consolidated
balance sheets of the Company and its subsidiaries, if any, as of the end of
such fiscal year, and consolidated statements of income and surplus,
consolidated statements of changes in financial position of the Company and
its subsidiaries and consolidated statements of changes in stockholders'
equity, if any, for such year, prepared in accordance with generally accepted
accounting principles and setting forth in each case in comparative form the
figures for the previous fiscal year, all in reasonable detail and certified
by independent public accountants of recognized national standing selected by
the Company; and

                  (b) As soon as practicable after the end of every fiscal
quarter and in any event within 45 days thereafter, an unaudited consolidated
balance sheet of the Company and its subsidiaries, if any, as of the end of
each such quarter, and consolidated statements of income, consolidated
statements of changes in financial condition and consolidated statements of
changes in stockholders' equity of the Company and its subsidiaries for such
period, prepared in accordance with generally accepted accounting principals,
subject to changes resulting from year-end audit adjustments.

         3.2 INSPECTION. The Company shall permit each Investor, at such
Investor's expense, to visit and inspect the Company's properties, to examine
its books of account and records and to discuss the Company's affairs,
finances and accounts with its officers, all at such reasonable times as may
be requested by the Investor provided, however, that the Company shall not be
obligated pursuant to this Section 3.2 to provide access to any information
which it reasonably considers to be a trade secret or similar confidential
information.

         3.3 ASSIGNMENT OF RIGHTS TO FINANCIAL INFORMATION. The rights
granted pursuant to this Section 3 may be assigned by Investors (or by any
permitted transferee of any such rights) only in connection with the transfer
to a single transferee of not less than 100,000 shares of Preferred Stock or
Common Stock issued upon conversion thereof, or a combination thereof
(including, for such purposes transfers by affiliates of a transferor) and
only so long as (i) the Company is given notice of any such assignment within
thirty (30) days of the date the same is effected, which notice shall
disclose the name of such assignee and provide a reasonably detailed
description of such assignee's business or principal occupation and the
circumstances surrounding such assignment, (ii) the Company reasonably
determines that the assignee is not a direct competitor or potential
competitor of the Company and (iii) if the Company reasonably believes that
it is necessary to protect proprietary information, the Company may require
that the assignee execute a confidentiality agreement as a condition to
receiving such information.

         3.4 TERMINATION OF COVENANTS. The covenants set forth in Section 3
shall terminate and be of no further force or effect after the earlier of (a)
the date upon which the first registration statement filed by the Company
under the Securities Act in connection with the firm commitment underwritten
public offering of its securities at an aggregate offering price of not less
than $10,000,000 and at a public offering price equal to or exceeding $5.50
per share (as adjusted for any


                                      -14-

<PAGE>

stock dividends, combinations, or splits with respect to such shares) becomes
effective, or (b) the date when none of the Preferred Stock is outstanding.

                                    SECTION 4

            AFFIRMATIVE COVENANT OF INVESTORS; RIGHT OF FIRST REFUSAL

         4.1 CONFIDENTIAL INFORMATION, ETC. Each Investor agrees that all
information received by it pursuant to Section 3, and any other information
relating to the Company's technology, processes or formulas that is disclosed
by the Company to any Investor in writing and is marked "Confidential," shall
be considered confidential information. Each Investor further agrees that it
shall hold all confidential information relating to the Company in confidence
and shall not disclose any such confidential information to any third party
other than its counsel or accountants nor shall such Investor use such
confidential information for any purpose other than evaluation of such
Investor's investment in the Company; provided, however, that the foregoing
obligation to hold in confidence and not to disclose confidential information
shall not apply to any such information that (a) was known to the public
prior to disclosure by the Company, (b) becomes known to the public through
no fault of such Investor, (c) is disclosed to such Investor on a
non-confidential basis by a third party having a legal right to make such
disclosure or (d) is independently developed by such Investor.

         4.2 RIGHT OF FIRST REFUSAL. The Company hereby grants to each
Purchaser (defined below) the right of first refusal to purchase its Pro Rata
Share (defined below) of all (or any part) of any New Securities (defined
below) that the Company may from time to time propose to sell and issue. Such
Purchaser's "Pro Rata Share," for purposes of this right of first refusal, is
the ratio of the number of shares of Common Stock (assuming conversion to
Common Stock of all shares of the Preferred Stock) then held by such
Purchaser to the total number of shares of Common Stock then outstanding
(assuming conversion to Common Stock of all outstanding shares of the
Company's Preferred Stock). This right of first refusal shall be subject to
the following provisions:

                  (a) "PURCHASER" shall mean, with respect to any issuance of
New Securities of the Company, each Founder who then holds any Founders'
Original Common Stock and each Investor who then holds any Preferred Stock
(or Common Stock issued upon conversion thereof).

                  (b) "NEW SECURITIES" shall mean any Common Stock or any
series or class of preferred stock including the Preferred Stock of the
Company, whether now authorized or not, and rights, options or warrants to
purchase said Common Stock or preferred stock, and securities of any type
whatsoever that are, or may become, convertible into or exchangeable for said
Common Stock or preferred stock; provided, however, that "New Securities"
does not include (i) securities issuable upon conversion of or with respect
to preferred stock or any future series of preferred stock; (ii) securities
issuable upon exercise of warrants to purchase up to an aggregate of 313,000
shares of Series B Preferred Stock, securities issuable upon exercise of
warrants to purchase up to an aggregate of 83,400 shares of Series C
Preferred Stock and securities issuable upon exercise of warrants to purchase
up to an aggregate of 165,955 shares of Series D Preferred Stock; (iii)
securities offered to the public pursuant to a registration statement filed
under the Securities Act;


                                      -15-

<PAGE>

(iv) securities issued pursuant to the acquisition of another corporation by
the Company by merger, purchase of substantially all of the assets or other
reorganization; (v) up to 5,825,000 shares of the Company's Common Stock (or
related options or warrants) that are issued to directors, officers or
employees of, or consultants to, the corporation pursuant to an agreement or
an option or purchase plan or another director, officer, employee or
consultant stock incentive program approved by the Board of Directors of the
Company; (vi) shares of the Company's Common Stock that are issued in
connection with technology licensing, corporate partnering, equipment leasing
or similar or related transactions and (vii) shares of the Company's Common
Stock or Preferred Stock issued in connection with any stock split, stock
dividend, or recapitalization by the Company.

                  (c) In the event that the Company proposes to undertake an
issuance of New Securities, it shall give each Purchaser written notice of
its intention, describing the type of New Securities, the price, and the
general terms upon which the Company proposes to issue the same. Each
Purchaser shall have five (5) days from the date of delivery of any such
notice to agree to purchase its pro rata share of such New Securities for the
price and upon the general terms specified in the notice by giving written
notice to the Company and stating therein the quantity of New Securities to
be purchased.

                  (d) In the event that Purchasers fail to exercise in full
the right of first refusal within said five (5) day period, the Company shall
have sixty (60) business days thereafter to sell (or enter into an agreement
pursuant to which the sale of New Securities covered thereby shall be closed,
if at all, within sixty (60) business days from the date of said agreement)
the New Securities respecting which the Purchasers' rights were not
exercised, at a price and upon general terms no more favorable to the
purchasers thereof than specified in the Company's notice. In the event the
Company has not sold the New Securities within said sixty (60) business day
period (or sold and issued new Securities in accordance with the foregoing
within sixty (60) business days from the date of said agreement), the Company
shall not thereafter issue or sell any New Securities, without first offering
such securities to the Purchasers in the manner provided above.

                  (e) The right of first refusal granted under this Agreement
shall expire upon the closing of the Company's first underwritten public
offering of Common Stock at an aggregate offering price of not less than
$10,000,000 and at a public offering price equal to or exceeding $5.50 per
share (as adjusted for any stock dividends, combinations, or splits with
respect to such shares) pursuant to a registration statement declared
effective under the Securities Act.

                  (f) This right of first refusal is nonassignable except to
any other Purchaser or to any parent, subsidiary or general or limited
partner or member of any Purchaser.

                                    SECTION 5

                                  MISCELLANEOUS

         5.1 GOVERNING LAW. This Agreement shall be governed by the laws of
the State of California as applicable to contracts entered into and performed
entirely within the State of California.


                                      -16-

<PAGE>

         5.2 SUCCESSORS AND ASSIGNS. Except as otherwise provided herein, the
provisions hereof shall inure to the benefit of, and be binding upon, the
successors, assigns, heirs, executors and administrators of the parties
hereto.

         5.3 ENTIRE AGREEMENT. This Agreement constitutes the full and entire
understanding and agreement between the parties with regard to the subject
matter hereof.

         5.4 RIGHTS OF INVESTORS AND FOUNDERS. Each Investor and Founder
shall have the absolute right to exercise or refrain from exercising any
right or rights that such Investor or Founder may have by reason of this
Agreement or the ownership of any Preferred Stock, including without
limitation the right to consent to the waiver of any obligation of the
Company under this Agreement to such Investor or Founder and to enter into an
agreement with the Company for the purpose of modifying this Agreement or any
agreement affecting any such modification, and such Investor or Founder shall
not incur any liability to any other Investor or holder of Preferred Stock or
Founder with respect to exercising or refraining from exercising any such
right or rights.

         5.5 NOTICES, ETC. All notices and other communications required or
permitted hereunder shall be in writing and shall be mailed by registered or
certified mail, postage prepaid, or facsimile or otherwise delivered by hand
or by messenger, addressed (a) if to an Investor or Founder, at such
Investor's or Founder's address set forth below or at such other address as
such Investor or Founder shall have furnished to the Company in writing, (b)
if to any other holder of Preferred Stock, at such address as such holder
shall have furnished the Company in writing or (c) if to the Company, one
copy shall be sent to its address set forth above and addressed to the
attention of the Corporate Secretary and another copy shall be sent to Wilson
Sonsini Goodrich & Rosati, 650 Page Mill Road, Palo Alto, CA 94304,
Attention: Michael J. O'Donnell, Esq., or at such other addresses as the
Company shall have furnished to the Investors and the Founders. All notices
and other communications mailed or sent by facsimile pursuant to the
provisions of this Section 5.5 shall be deemed delivered when mailed or sent
by facsimile.

         5.6 COUNTERPARTS. This Agreement may be executed in counterparts,
each of which shall be enforceable against the party actually executing such
counterpart, and which together shall constitute one instrument.

         5.7 SEVERABILITY. In the event that any provision of this Agreement
becomes or is declared by a court of competent jurisdiction to be illegal,
unenforceable or void, this Agreement shall continue in full force and effect
without said provision; provided that no such severability shall be effective
if it materially changes the economic benefit of this Agreement to any party.

         5.8 APPROVAL OF AMENDMENTS AND WAIVERS. Any term of this agreement
may be amended or terminated and the observance of any term of this Agreement
may be waived (either generally or in a particular instance and either
retroactively or prospectively) with the written consent of the Company and
Investors (or their transferees) holding at least sixty-six and two-thirds
percent (66 2/3%) of the then outstanding shares of Registrable Securities,
excluding from the determination of such percentage (both in determining the
total number of such shares outstanding and the number of such shares
consenting or not consenting) all shares previously disposed of by


                                      -17-

<PAGE>

Investors or their transferees pursuant to one or more registration
statements under the Securities Act or pursuant to Rule 144 thereunder;
provided, however, that no such amendment or waiver shall adversely affect
the right of any Founder to participate in registrations under Section 2.6 of
this Agreement as provided for in Section 2.16 without such Founder's written
consent; it being understood, however, that the amendment of this Agreement
to increase the number of shares defined as Registrable Securities or to add
additional parties as Investors shall be deemed not to adversely affect such
right under Section 2.6. Any amendment, termination or waiver effected in
accordance with this section shall be binding upon each Founder, each
Investor, each of their transferees and the Company. Each Founder and each
Investor acknowledges that, subject to the limitations contained in the first
sentence of this Section 5.8, by the operation of this Section 5.8 the
holders of sixty-six and two-thirds percent (66 2/3%) of the outstanding
Registrable Securities may have the right and power to diminish or eliminate
all rights of such Founder or such Investor under this Agreement as provided
for above. Notwithstanding anything in this Agreement to the contrary,
however, no written consent of the Investors or Founders shall be required to
amend this Agreement to add additional parties to this Agreement as Investors
who are purchasers at Subsequent Closings of the Series E Agreement pursuant
to Section 1.3 of the Series E Agreement.




                           [INTENTIONALLY LEFT BLANK]










                                      -18-

<PAGE>

         The foregoing Agreement is hereby executed as of the date first above
written.

THE COMPANY:

CIPHERGEN BIOSYSTEMS, INC.

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

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























    (SIGNATURE PAGE TO FOURTH AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT)

<PAGE>

THE INVESTORS:



ATLAS VENTURE FUND V,L.P.

By:  Atlas Venture Associates V, L.P.
        its general partner

   By:  Atlas Venture Associates V, Inc.
        Its general partner





--------------------------------
Vice President



ATLAS VENTURE PARALLEL FUND V-A.C.V.

By:  Atlas Venture Associates V, L.P.
        its general partner

By:  Atlas Venture Associates V, Inc.
        Its general partner





--------------------------------
Vice President



ATLAS VENTURE PARALLEL FUND V-B C.V.

By:  Atlas Venture Associates V, L.P.
        its general partner

By:  Atlas Venture Associates V, Inc.
        Its general partner





--------------------------------
Vice President



    (SIGNATURE PAGE TO FOURTH AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT)

<PAGE>


ATLAS VENTURE ENTREPRENEURS' FUND V,L.P.

By:  Atlas Venture Associates V, L.P.
        its general partner

By:  Atlas Venture Associates V, Inc.
        Its general partner





-----------------------
Vice President





MORGAN STANLEY DEAN WITTER

VENTURE PARTNERS IV, L.P.

By:    MSDW VENTURE PARTNERS IV, LLC,
       AS GENERAL PARTNER

By:    MSDW VENTURE PARTNERS IV, INC.,
       AS MEMBER





By:
     --------------------------------
       Name:

       Title:



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

       Name:

       Title:


    (SIGNATURE PAGE TO FOURTH AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT)

<PAGE>

ESSEX PRIVATE PLACEMENT FUND III - A, Limited Partnership

By:  Essex Investment Management Company, LLC its General Partner


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

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



ESSEX PRIVATE PLACEMENT FUND III - B, Limited Partnership

By:  Essex Investment Management Company, LLC its General Partner


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

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



ORBIMED ADVISORS, LLC


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

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



AP ANLAGE Private Bank AG


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

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


    (SIGNATURE PAGE TO FOURTH AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT)

<PAGE>

CLARIDEN BANK. a CREDIT SUISSE GROUP company


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

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



AMADEUS CAPITAL PARTNERS LIMITED


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

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



PENTECH FINANCIAL SERVICES, INC.


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

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



CHINA DEVELOPMENT INDUSTRIAL BANK INC.


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

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


    (SIGNATURE PAGE TO FOURTH AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT)

<PAGE>

FIRST BIO VENTURE CAPITAL CORPORATION of Cheng Xin Venture Capital Corp


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

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



CENTRAL INVESTMENT HOLDING (B.V.I.) CO., LTD.


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

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



GRAND CAPITAL INTERNATIONAL LIMITED of Bank SinoPac


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

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



MDS, INC.


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

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




    (SIGNATURE PAGE TO FOURTH AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT)

<PAGE>


S. R. ONE, LIMITED


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

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



MDS LIFE SCIENCES TECHNOLOGY BARBADOS INVESTMENT TRUST


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

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



MDS LIFE SCIENCES TECHNOLOGY FUND LIMITED PARTNERSHIP, by its General Partner,
MDS Life Sciences Technology Fund (GP) Inc.


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

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



MDS LIFE SCIENCES TECHNOLOGY FUND USA, L.P.
by its General Partner, MDS Capital USA (GP) Inc.


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

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




    (SIGNATURE PAGE TO FOURTH AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT)

<PAGE>


THE HEALTH CARE AND BIOTECHNOLOGY VENTURE FUND
by its Manager, MDS Capital Corp


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

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



STANFORD RESEARCH SYSTEMS


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

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



WILLIAM R. GREEN


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

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



JAMES AND LINDA GINSBURG


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

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



FALCON TECHNOLOGY PARTNERS, L.P.


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

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



    (SIGNATURE PAGE TO FOURTH AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT)

<PAGE>


FORWARD VENTURES II, L.P.


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

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



ICNA, LTD.


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

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



JOHN A. YOUNG, TRUSTEE for the Young
       Family Trust


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

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



DIANA K. YOUNG


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

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



GREGORY S. YOUNG


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

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


    (SIGNATURE PAGE TO FOURTH AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT)

<PAGE>


JOHN PETER YOUNG


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

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



HLM/ CB FUND L.P.


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

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



TURTLE & COMPANY c/o Nuland & Arshad, Inc.


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

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



HOOVER ASSOCIATES


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

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



THE MACKOWSKI FAMILY TRUST
      c/o Mackowski & Shepler


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

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


    (SIGNATURE PAGE TO FOURTH AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT)

<PAGE>


WATERVIEW TRUST


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

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



JOHNATHAN J. KENT


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

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



DANIEL VAPNEK


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

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



GUARANTEE TRUST COMPANY FBO
      Lenita L. Rich IRA, Dated 8-2-91, No. 20186123 BT Alex Brown


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

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



ONE AND COMPANY
     as Nominee for Welch & Forbes c/o Charles Haydock


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

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


    (SIGNATURE PAGE TO FOURTH AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT)

<PAGE>


DEAN V. AMBROSE


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

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



EDWARD O. ANSELL


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

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



ROBERT SHEPLER c/o Mackowski & Shepler


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

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



PETER F. DRAKE c/o Prudential Vector Healthcare


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

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



ROBERT AND LORI LUTHER


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

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


    (SIGNATURE PAGE TO FOURTH AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT)

<PAGE>


IKIKO CORPORATION c/o Nuland & Arshad, Inc.


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

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



ANTHONY J. SINSKEY c/o Department of Biology


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

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



R. ANGUS WEST c/o The Boston Family Office. L.L.C.


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

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



MICHAEL G. AND OLWEN PAGE c/o Prudential Vector Healthcare


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

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



ROBERT A. SHAW AND MAUREEN MCLAUGHLIN, Trustees UTD 12-14-90


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

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


    (SIGNATURE PAGE TO FOURTH AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT)

<PAGE>

                                   SCHEDULE A

                         FOUNDERS' ORIGINAL COMMON STOCK

<TABLE>
<CAPTION>
SHAREHOLDER                                     ISSUE DATE            NUMBER OF SHARES
-----------                                     ----------            ----------------
<S>                                             <C>                   <C>
Dean V. Ambrose                                  12/27/93                 31,648

Edward O. Ansell                                 12/27/93                 31,648

Steven M. Clark                                  12/27/93                 107,500

Jonathan J. Kent                                 12/27/93                 153,889

Stephen B. H. Kent                               12/27/93                 250,000
</TABLE>








    (SIGNATURE PAGE TO FOURTH AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT)

<PAGE>

                                   SCHEDULE B

                        INVESTORS' ORIGINAL COMMON STOCK

<TABLE>
<CAPTION>
SHAREHOLDER                                     ISSUE DATE            NUMBER OF SHARES
-----------                                     ----------            ----------------
<S>                                             <C>                   <C>
S.R. One, Limited                                12/29/93                 100,000

Forward Ventures II, L.P.                        12/29/93                  75,000
</TABLE>


























    (SIGNATURE PAGE TO FOURTH AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT)