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                                                                     EXHIBIT 4.2

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                           BARRIER THERAPEUTICS, INC.

                 AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT

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                                TABLE OF CONTENTS

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                                                                                               PAGE
<S>                                                                                            <C>
ARTICLE 1   GENERAL........................................................................      1
    1.1   Certain Definitions..............................................................      1
ARTICLE 2   REGISTRATION...................................................................      4
    2.1   Demand Registration..............................................................      4
    2.2   Piggyback Registrations..........................................................      6
    2.3   Form S-3 Registration............................................................      7
    2.4   Initial Public Offering..........................................................      8
    2.5   Expenses of Registration.........................................................      8
    2.6   Obligations of the Company.......................................................      8
    2.7   Furnishing Information...........................................................     11
    2.8   Indemnification..................................................................     11
    2.9   Assignment of Registration Rights................................................     13
    2.10  Amendment of Registration Rights.................................................     14
    2.11  Limitation on Subsequent Registration Rights.....................................     14
    2.12  "Market Stand-Off" Agreement; Agreement to Furnish Information...................     14
    2.13  Rule 144 Reporting...............................................................     15
ARTICLE 3   MISCELLANEOUS..................................................................     15
    3.1   Governing Law....................................................................     15
    3.2   Jurisdiction.....................................................................     15
    3.3   Survival.........................................................................     16
    3.4   Successors and Assigns...........................................................     16
    3.5   Entire Agreement.................................................................     16
    3.6   Severability.....................................................................     16
    3.7   Amendment and Waiver.............................................................     17
    3.8   Delays or Omissions..............................................................     17
    3.9   Notices..........................................................................     17
    3.10  Headings.........................................................................     17
    3.11  Counterparts.....................................................................     17
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                                        i
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                 AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT

                  This AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT (the
"Agreement") is entered into as of this 20th day of April, 2004, by and among
Barrier Therapeutics, Inc., a Delaware corporation (the "Company"), and the
Investors listed on Exhibit A hereto (collectively, the "Investors," and each as
"Investor").

                                    RECITALS

                  WHEREAS, the Company, the holders (the "Series A Investors")
of the Company's Series A Convertible Preferred Stock (the "Series A Preferred
Stock") and the holders (the "Series B Investors") of the Company's Series B
Convertible Preferred Stock (the "Series B Preferred Stock") have entered into
that certain Investor Rights Agreement dated as of May 7, 2002, as amended as of
October 23, 2003 in connection with the sale of the Company's Series C
Convertible Preferred Stock (the "Series C Preferred Stock") to add the holders
of Series C Preferred Stock (the "Series C Investors") as parties hereto (the
"Original Investor Rights Agreement"), pursuant to which the Company has granted
registration rights and certain other rights to the Series A Investors, the
Series B Investors and the Series C Investors;

                  WHEREAS, the Company has filed Registration Statement No.
333-112539 on Form S-1 (the "Registration Statement") relating to an initial
public offering of the Company's Common Stock (the "IPO") and the Company and
the Investors desire for Articles 3 and 4 of the Original Investor Rights
Agreement to terminate immediately prior to the consummation of the IPO (the
"Effective Time"); and

                  WHEREAS, this Agreement amends and restates in its entirety
the Original Investor Rights Agreement to become effective at the Effective
Time.

                  NOW, THEREFORE, in consideration of the mutual promises,
representations, warranties, covenants and conditions set forth herein, the
parties mutually agree as follows:

                                    ARTICLE 1

                                     GENERAL

         1.1      Certain Definitions. As used in this Agreement the following
terms shall have the following meanings:

                  "Affiliate", as applied to any individual or entity, shall
mean an individual or entity directly or indirectly (through one or more
intermediaries) controlling, controlled by or under common control with the
first individual or entity. As applied to an individual, "Affiliate" shall
include any member of such individual's immediate family or any trust for the
benefit of such family member or individual and as applied to any entity,
"Affiliate" shall include any subsidiary, parent, member, limited partner,
general partner, entity under common control of such general partner or its
members, partners or stockholders.

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                   "Common Stock" means the Company's authorized common stock
with $0.0001 par value per share.

                  "Exchange Act" means the Securities Exchange Act of 1934, as
amended, or any successor Federal statute in effect, and the rules and
regulations of the SEC promulgated thereunder, all as the same may from time to
time be in effect.

                  "Form S-3" means such form promulgated under the Securities
Act as in effect on the date hereof or any successor registration form under the
Securities Act subsequently adopted by the SEC which permits inclusion or
incorporation of substantial information by reference to other documents filed
by the Company with the SEC.

                  "Holder" means any Person owning of record Registrable
Securities that have not been sold to the public or any assignee of record of
such Registrable Securities in accordance with Section 2.10 hereof.

                  "Initial Public Offering" means the Company's first firm
commitment underwritten public offering of its Common Stock registered under the
Securities Act.

                  "Other Shares" shall mean at any time those shares of Common
Stock which do not constitute Primary Shares or Registrable Securities.

                  "Person" shall be construed in the broadest sense and means
and includes a natural person, a partnership, a corporation, an association, a
joint stock company, a limited liability company, a trust, a joint venture, an
unincorporated organization and any other entity and any federal, state,
municipal, foreign or other government, governmental department, commission,
board, bureau, agency or instrumentality, or any private or public court or
tribunal.

                  "Primary Shares" shall mean, at any time, the authorized but
unissued shares of Common Stock or Common Stock held by the Company in its
treasury.

                  "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
effectiveness of such registration statement or document.

                  "Registrable Securities" means (a) Common Stock issued or
issuable upon conversion of the Shares; (b) any other Common Stock held, or
hereafter acquired, by the Investors or issuable to the Investors pursuant to
options, warrants or convertible securities; and (c) any Common Stock issued as
(or issuable upon the conversion or exercise of any warrant, right or other
security which is issued as) a dividend or other distribution with respect to,
or in exchange for or in replacement of, such above-described securities.
Notwithstanding the foregoing, Registrable Securities shall not include any
securities sold by a Person to the public pursuant to a registration statement
which has been declared effective, or Rule 144 or sold in a private transaction
in which the transferor's rights under Article II of this Agreement are not
assigned, in each case where the restrictive legends and transfer registrations
with respect to the Common Stock are removed and the Common Stock in the hands
of the purchaser is freely transferable without any restriction or registration
under the Securities Act in any public or private transaction.

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                  "Registrable Securities then outstanding" shall be the number
of shares determined by calculating the total number of shares of Common Stock
that are Registrable Securities and either (a) are then issued and outstanding
or (b) are issuable pursuant to then exercisable or convertible securities.

                  "Registration Expenses" mean all expenses incurred by the
Company in complying with Sections 2.2, 2.3 and 2.4 hereof, including, without
limitation, all registration and filing fees (including all expenses incident to
listing the Registrable Securities on a national securities exchange), printing
expenses, fees and disbursements of counsel for the Company, reasonable fees and
disbursements of the Stockholders' Counsel (as defined in Section 2.6(i)) (which
shall not exceed $50,000), 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); provided, that no fees or disbursements of the JJDC
Counsel (as defined in Section 2.6(i)) shall be paid by the Company.

                  "Rule 144" shall mean Rule 144 promulgated under the
Securities Act or any successor rule thereto.

                  "Sale Of The Company" means (i) the sale of all or
substantially all of the Company's assets in one transaction or a series of
transactions, (ii) the sale or transfer of the outstanding capital stock of the
Company, or (iii) the merger or consolidation of the Company with or into
another Person or entity, in each case in clauses (ii) and (iii) above under
circumstances in which the holders of a majority in voting power of the
outstanding capital stock of the Company, immediately prior to such transaction,
own less than a majority in voting power of the outstanding capital stock of the
Company or the surviving or resulting corporation or acquirer, as the case may
be, immediately following such transaction. A sale (or multiple related sales)
of one or more Subsidiaries of the Company (whether by way of merger,
consolidation, reorganization or sale of all or substantially all assets or
securities) which constitutes all or substantially all of the consolidated
assets of the Company shall be deemed a Sale Of The Company.

                  "SEC" or "Commission" means the Securities and Exchange
Commission.

                  "Securities Act" means the Securities Act of 1933, as amended
or any successor Federal statute and the rules and regulations of the Commission
promulgated thereunder, all as the same may be in effect from time to time.

                  "Selling Expenses" mean all underwriting discounts and selling
commissions applicable to the sale.

                  "Shares" mean shares of the Company's Series A Preferred
Stock, Series B Preferred Stock and Series C Preferred Stock held, or hereafter
acquired, by the Investors and their permitted assigns.

                  "Stockholders Agreement" means the Company's Amended and
Restated Stockholders Agreement dated the date hereof.

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                                    ARTICLE 2

                                  REGISTRATION

         2.1      Demand Registration.

                  (a)      Subject to the conditions of this Section 2.1, if the
Company receives a request from the Holders of at least fifty percent (50%) of
the Registrable Securities then outstanding (the "Initiating Holders") that the
Company register shares with an aggregate offering price of at least $5,000,000,
then the Company shall, within fifteen (15) days after the receipt thereof, give
written notice of such request to all non-Initiating Holders. A non-Initiating
Holder must notify the Company within thirty (30) days of receipt of such
written notice if such non-Initiating Holder so desires to have its Registrable
Securities registered. The Company will use best efforts to effect, as soon as
practicable, the registration of all Registrable Securities that the Holders
(both Initiating Holders and non-Initiating Holders) request to be registered.

                  (b)      If the Initiating Holders intend to distribute the
Registrable Securities by means of an underwriting, they shall so advise the
Company as a part of their demand pursuant to this Section 2.1 and the Company
shall include such information in the notice referred to in Section 2.2(a). In
such event, the right of any Holder to include its Registrable Securities in
such registration shall be conditioned upon participation in such underwriting.
The underwriter or underwriters for such offering shall be a nationally
recognized underwriter or underwriters selected by the Holders owning a majority
of the Registrable Securities requested to be included in such offering and
reasonably acceptable to the Company and such underwriter or underwriters shall
enter into a reasonable and customary underwriting agreement with the Company.
Notwithstanding any other provision of this Section 2.1, if the underwriter
advises the Company that marketing factors require a limitation of the number of
securities to be underwritten (including Registrable Securities) then the
Company shall so advise all participating Holders, and the number of shares that
may be included in the underwriting and registration shall be allocated pro rata
among the participating Holders in accordance with the number of Registrable
Securities held by such Holders; provided, however, that the number of shares of
Registrable Securities to be included in such underwriting and registration
shall not be reduced unless and until all other securities to be sold by the
Company and any Persons that are not Holders are first entirely excluded from
the underwriting and registration.

                  (c)      The Company shall not be required to effect a
registration pursuant to this Section 2.1:

                           (i)      prior to the earlier of (A) the fifth
anniversary of the Closing Date (as defined in the Series C Securities
Acquisition Agreement) and (B) six months following the effective date of the
registration statement pertaining to the Initial Public Offering;

                           (ii)     after the Company has effected two
registrations pursuant to this Section 2.1, and such registrations have been
declared or ordered effective and maintained effective for (A) one hundred
twenty (120) days beyond the effective date or (B) until all shares so
registered have been sold, whichever period is longer (provided, however, that
such two registrations shall not include any registration pursuant to this
Section 2.1 in which the number

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of Registrable Securities registered is reduced by more than twenty percent
(20%) of the number of Registrable Securities that the Holders requested to be
registered);

                           (iii)    during the period starting with the date of
filing of and ending on the date ninety (90) days following the effective date
of a registration statement pertaining to any underwritten public offering made
pursuant to this Section 2.1 or in which the Holders were given the opportunity
to participate pursuant to Section 2.2 for not less than thirty percent (30%) of
the amount of the offering; provided that each registration statement was
declared or ordered effective and maintained effective for (A) one hundred
twenty (120) days beyond the effective date or (B) until all shares so
registered have been sold, whichever period is longer;

                           (iv)     if within ten (10) days of receipt of a
written request from the Initiating Holders pursuant to Section 2.1(a) the
Company shall furnish to the Initiating Holders a certificate signed by an
officer of the Company stating either (A) that in the good faith judgment of the
Board of Directors, it would be seriously detrimental to the Company and its
stockholders for such registration statement to be effected at such time or (B)
the Company intends to make its Initial Public Offering within sixty (60) days
of the date such request was received from the Initiating Holders, the Company
shall have the right to defer such filing for a period of not more than sixty
(60) days after receipt of the request of the Initiating Holders; provided,
that, such right to delay a request shall be exercised by the Company not more
than twice in any twelve (12) month period; provided, further, that the Company
shall not disclose any information that could be deemed material non-public
information of the Company to any of the Initiating Holders during such delayed
period; and

                           (v)      if the Initiating Holders propose to dispose
of shares of Registrable Securities that may be immediately registered on Form
S-3 pursuant to a request made pursuant to Section 2.3 below.

                  (d)      A requested registration under this Section 2.1 may
be rescinded prior to such registration being declared effective by the
Commission by written notice to the Company from the Initiating Holder;
provided, however, that such rescinded registration shall not count as a
registration initiated pursuant to this Section 2.1 if the Company shall have
been reimbursed (pro rata by the Initiating Holders or in such other proportion
as they may agree) for all out-of-pocket expenses incurred by the Company in
connection with such rescinded registration; provided further, however, that
such Initiating Holders shall not be required to reimburse the Company if such
rescission shall have been caused by, or made in response to, the material
adverse effect of an event on the business, prospects, properties, condition
(financial or otherwise) or operations of the Company.

         2.2      Piggyback Registrations. If the Company at any time proposes
for any reason to register Primary Shares or Other Shares under the Securities
Act (other than (a) a rights offering, (b) a registration on Form S-4 or Form
S-8 promulgated under the Securities Act or any successor forms thereto, or (c)
in connection with the Company's Initial Public Offering), the Company shall
notify all Holders at least thirty (30) days prior to the filing of any
registration statement and will afford each Holder an opportunity to include in
such registration statement all or part of the Registrable Securities held by
such Holder on the same terms and conditions as the other shares participating
in the underwriting. Each Holder desiring to include Registrable

                                     - 5 -
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Securities in any such registration statement shall notify the Company within
twenty (20) days after delivery of the notice from the Company. Such notice
shall state the intended method of disposition of the Registrable Securities by
such Holder. If a Holder decides not to include all of its Registrable
Securities in any registration statement filed by the Company, such Holder shall
nevertheless continue to have the right to include any Registrable Securities in
any subsequent registration statement or registration statements as may be filed
by the Company, all upon the terms and conditions set forth herein.

                  (a)      Underwriting. If the registration statement under
which the Company gives notice under this Section 2.2 is for an underwritten
offering, the Company shall so advise the Holders. In such event, the right of
any Holder to be included in a registration pursuant to this Section 2.2 shall
be conditioned upon the Holder's participation in the underwriting.
Notwithstanding any other provision of the Agreement, if the underwriter
determines in good faith that marketing factors require a limitation of the
number of shares to be underwritten, the number of shares that may be included
in the underwriting shall be allocated as follows, first, the Primary Shares
being registered by the Company, second, the Registrable Securities requested to
be included in such registration by the Holders pro rata based on the total
number of Registrable Securities held by such Holders, and third, the Other
Shares requested to be registered by any other stockholder of the Company on a
pro rata basis based on the total number of shares held by such Persons. No such
reduction shall reduce the amount of securities of the selling Holders included
in the registration below thirty percent (30%) of the total amount of securities
included in such registration.

                  (b)      Right to Terminate Registration. The Company shall
have the right to terminate or withdraw any registration initiated by it under
this Section 2.1 prior to the effectiveness of such registration whether or not
any Holder has elected to include securities in such registration. The
Registration Expenses of such withdrawn registration shall be borne by the
Company in accordance with Section 2.4 hereof.

                  (c)      Inclusion of Common Holders. No stockholder of the
Company who is not a Holder shall be granted piggyback registration rights that
would reduce the number of shares that could be included by the Holders without
the consent of Holders owning at least two-thirds (2/3) of the Registrable
Securities.

         2.3      Form S-3 Registration.

                  (a)      If the Company shall receive from any Holder or
Holders a request that the Company effect a registration on Form S-3 or any
similar short-form registration statement with respect to all or a part of the
Registrable Securities, the Company shall:

                           (i)      promptly give notice of the proposed
registration, and any related qualification or compliance, to all other Holders
and shall offer to include in such proposed registration any Registrable
Securities requested to be included in such proposed registration by such
Holders who respond in writing to the Company's notice within 30 days after
delivery of such notice (which response shall specify the number of Registrable
Securities proposed to be included in such registration); and

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                           (ii)     promptly effect such registration and all
such qualifications and compliances as would permit or facilitate the sale and
distribution of the Registrable Securities specified in such request, together
with the Registrable Securities of any other Holder or Holders joining in such
request by notice to the Company given within thirty (30) days after receipt of
such notice from the Company.

                  (b)      Notwithstanding anything to the contrary contained
herein, the Company shall not be obligated to effect any registration,
qualification or compliance pursuant to this Section 2.3:

                           (i)      if Form S-3 is not available for such
offering by the Holders;

                           (ii)     if the Holders, together with the holders of
any other securities of the Company entitled to inclusion in such registration,
propose to sell Registrable Securities and such other securities (if any) at an
aggregate price to the public of less than $1,000,000;

                           (iii)    if the Company shall furnish to the Holders
a certificate signed by the President or Chief Executive Officer of the Company
stating that in the good faith judgment of the Board of Directors, it would be
seriously detrimental to the Company and its stockholders for such Form S-3
registration to be effected at such time, in which event the Company shall have
the right to defer the filing of the Form S-3 registration statement for a
period of not more than thirty (30) days after receipt of the request of the
Holder or Holders under this Section 2.3; provided, that such right to delay a
request shall be exercised by the Company not more than twice in any twelve (12)
month period;

                           (iv)     if the Company has, within the twelve (12)
month period preceding the date of such request, already effected three (3)
registrations on Form S-3 for the Holders pursuant to this Section 2.3; or

                           (v)      in any particular jurisdiction in which the
Company would be required to qualify to do business or to execute a general
consent to service of process in effecting such registration, qualification or
compliance where it would not otherwise be required so to do.

                  (c)      Registrations effected pursuant to this Section 2.3
shall not be counted as demands for registration or registrations effected
pursuant to Section 2.1. If the initiating Holders intend to distribute
Registrable Securities pursuant to an underwriting, they shall so advise the
Company in the demand pursuant to Section 2.1(a).

                  (d)      After the Company's Initial Public Offering, the
Company will use commercially reasonable efforts to qualify for the registration
of its shares of Common Stock on Form S-3.

         2.4      Initial Public Offering. In connection with the Initial Public
Offering, the Company shall grant the Series A Investors, Series B Investors and
Series C Investors a right to purchase five percent (5%) of the shares (the "IPO
Shares") of Common Stock being offered in such public offering; provided,
however, that the Company shall not grant such right to an Investor if (i) with
respect to the Series C Investors only, the Initial Public Offering occurs prior

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to the first anniversary of the date hereof or (ii) compliance with the
provisions of this Section 2.4 would violate Section 5 of the Securities Act.
Any shares offered and sold to Investors under this Section 2.4 shall be offered
to the Investors (with Investors permitted to reallocate all or any portion of
their respective IPO Shares to Affiliates) pro-rata based upon the number of
shares of Common Stock (on an as converted basis) held by each Investor divided
by the total number of shares of Common Stock held by all Investors. Shares not
accepted by an Investor or its Affiliates shall not be reallocated among those
Investors electing to purchase IPO Shares. In the event that an Investor is not
permitted to purchase IPO Shares as a result of the restrictions contained in
clause (i) or (ii) above, the Company shall sell to such Investor who is a
"qualified institutional buyer" (as such term is defined in Rule 144A
promulgated under the Securities Act) and to such Investor who is subject to
Regulation S (promulgated under the Securities Act) a number of shares of Common
Stock equal to its pro rata portion of IPO Shares at the same gross purchase
price as the IPO Shares. Nothing in this Section 2.4 shall limit any Investor or
any Affiliate of any Investor from purchasing shares of Common Stock in the
Initial Public Offering that are not IPO Shares.

         2.5      Expenses of Registration. Except as specifically provided
herein, all Registration Expenses incurred in connection with any registration
under Section 2.1, Section 2.2 or Section 2.3 herein shall be borne by the
Company. All Selling Expenses incurred in connection with any registrations
hereunder shall be borne by the Persons selling the securities in proportion to
the number of securities sold by such seller or sellers.

         2.6      Obligations of the Company. Whenever required to register any
Registrable Securities, the Company shall, as expeditiously as reasonably
possible:

                  (a)      Use commercially reasonable efforts to prepare and
file with the SEC a registration statement with respect to such Registrable
Securities and to cause such registration statement to become effective, and,
upon the request of the selling Holders of a majority of the Registrable
Securities registered thereunder, keep such registration statement effective for
up to 120 days for a registration pursuant to Section 2.1 and for up to 180 days
for a registration pursuant to Section 2.3 or, if earlier, until the Holder or
Holders have completed the distribution related thereto;

                  (b)      Use its reasonable best efforts to prepare and file
with the SEC 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 for the
applicable period set forth in paragraph (a) above and to cause such amendments
and supplements to become and remain effective;

                  (c)      Furnish to the Holders and each underwriter such
number 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;

                  (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

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be reasonably requested by the Holders and register such securities with or
obtain the approval of such other governmental authorities as may be necessary
by virtue of the business and operations of the Company to enable the seller or
sellers thereof to consummate the disposition of such Registrable Securities;
provided, that the Company shall not be required in connection 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 where it would not
otherwise be required so to do but for this subparagraph;

                  (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(s) of such offering;

                  (f)      Notify on a timely basis 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 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 and promptly file such amendments and supplements as
may be necessary so that, as thereafter delivered to such Holders, such
prospectus shall not include an untrue statement of material fact or omit to
state a material fact required to be stated therein or necessary to make the
statements therein, in light of the circumstances under which they were made,
not misleading and use its best efforts to cause each such amendment and
supplement to become and remain effective;

                  (g)      Use its best efforts to furnish, on the date that
such Registrable Securities are delivered to the underwriters for sale, if such
securities are being sold through underwriters, (i) an opinion, dated as of such
date, of the counsel representing the Company for the purposes of such
registration, in form and substance as is customarily given to underwriters in
an underwritten public offering, addressed to the underwriters, if any, and (ii)
a letter dated as of such date, from the independent certified public
accountants of the Company, in form and substance as is customarily given by
independent certified public accountants to underwriters in an underwritten
public offering addressed to the underwriters;

                  (h)      Make available for inspection by the Holders, any
underwriter participating in any disposition pursuant to such registration
statement and any attorney, accountant or other agent retained by any such
Holder or underwriter (collectively, the "Inspectors"), all pertinent financial,
business and other records, pertinent corporate documents and properties of the
Company (collectively, the "Records"), as shall be reasonably necessary to
enable them to exercise their due diligence responsibility, and cause the
Company's officers, directors and employees to supply all information (together
with the Records, the "Information") reasonably requested by any such Inspector
in connection with such Registration Statement (and any of the Information which
the Company determines in good faith to be confidential, and of which
determination the Inspectors are so notified, shall not be disclosed by the
Inspectors unless (A) the disclosure of such Information is necessary to avoid
or correct a misstatement or omission in the registration statement, (B) the
release of such Information is ordered pursuant to a subpoena or other order
from a court of competent jurisdiction, (C) such Information has been made
generally available to the public, and (D) the seller of Registrable Securities
agrees that it

                                     - 9 -
<PAGE>

will, upon learning that disclosure of such Information is sought in a court of
competent jurisdiction, give notice to the Company and allow the Company, at the
Company's expense, to undertake appropriate action to prevent disclosure of the
Information deemed confidential);

                  (i)      At least five business days before filing any
registration statement that registers such Registrable Securities, a prospectus
relating thereto and any amendments or supplements relating to such registration
statement or prospectus, furnish to (A) a single counsel (who may be in-house
counsel to an Investor) (the "Stockholders' Counsel") designated by the holders
of a majority of the Registrable Securities being sold and (B) a single counsel
(the "JJDC Counsel"), designated by Johnson & Johnson Development Corporation
("JJDC") copies of all such documents proposed to be filed, which shall be
subject to reasonable approval of the Stockholders' Counsel and, with respect to
any sections thereof that reference or relate to the intellectual property,
products or businesses of, or otherwise relate to, JJDC or any of its
affiliates, the reasonable approval of the JJDC Counsel (it being understood
that such five-business-day period need not apply to successive drafts of the
same document proposed to be filed so long as such successive drafts are
supplied to such counsel in advance of the proposed filing by a period of time
that is customary and reasonable under the circumstances);

                  (j)      Notify the Stockholders' Counsel and the JJDC Counsel
promptly in writing (i) of any comments by the Commission with respect to such
registration statement or prospectus or any amendment or supplement thereto, or
any request by the Commission for the amending or supplementing thereof or for
additional information with respect thereto, (ii) of the issuance by the
Commission of any stop order suspending the effectiveness of such registration
statement or prospectus or any amendment or supplement thereto or the initiation
of any proceedings for that purpose and (iii) of the receipt by the Company of
any notification with respect to the suspension of the qualification of such
Registrable Securities for sale in any jurisdiction or the initiation or
threatening of any proceeding for such purposes;

                  (k)      provide a transfer agent and registrar (which may be
the same entity and which may be the Company) for such Registrable Securities;

                  (l)      list such Registrable Securities on any national
securities exchange on which the Common Stock is listed or, if the Common Stock
is not listed on a national securities exchange, use its best efforts to qualify
such Registrable Securities for inclusion on the automated quotation system of
the National Association of Securities Dealers, Inc. the "NASD"), National
Market System ("NMS"), or such other national securities exchange as the holders
of a majority of such Registrable Securities shall request included in such
registration; and

                  (m)      otherwise use commercially reasonable efforts to
comply with all applicable rules and regulations of the Commission, and make
available to its stockholders, as soon as reasonably practicable, earnings
statements which need not be audited covering a period of 12 months beginning
within three months after the effective date of the registration statement,
which earnings statements shall satisfy the provisions of Section 11(a) of the
Securities Act.

         2.7      Furnishing Information. It shall be a condition precedent to
the obligations of the Company to take any action pursuant to Section 2.1, 2.2
or 2.3 that the selling Holders shall furnish to the Company such information
regarding themselves, the Registrable Securities held

                                     - 10 -
<PAGE>

by them and the intended method of disposition of such securities as shall be
reasonably required to effect the registration of their Registrable Securities.

         2.8      Indemnification. In the event any Registrable Securities are
included in a registration statement under Sections 2.1, 2.2 or 2.3:

                  (a)      To the extent permitted by law, the Company will
indemnify and hold harmless each Holder and the partners, officers, directors,
stockholders, employees and agents of each Holder, any underwriter (as defined
in the Securities Act) for such Holder and each Person, if any, who controls
such Holder or underwriter within the meaning of the Securities Act or the
Exchange Act, against any losses, claims, damages, or liabilities (joint or
several) to which they may become subject under the Securities Act, the Exchange
Act or other federal or state law, insofar as such losses, claims, damages or
liabilities (or actions in respect thereof) arise out of or are based upon any
of the following statements, omissions or violations (collectively a
"Violation") by the Company: (i) any untrue statement or alleged untrue
statement of a material fact contained in such registration statement, including
any preliminary prospectus or final prospectus contained therein or any
amendments or supplements thereto, or any document incident to the registration
or qualification of any Registrable Securities, (ii) the omission or alleged
omission to state therein a material fact required to be stated therein, or
necessary to make the statements therein not misleading, or (iii) any violation
or alleged violation by the Company of the Securities Act, the Exchange Act, any
state securities law or any rule or regulation promulgated under the Securities
Act, the Exchange Act or any state securities law in connection with the
offering covered by such registration statement; and the Company will pay as
incurred to each such Holder, partner, officer, director, stockholder, employee,
agent, underwriter or controlling Person for any legal or other expenses
reasonably incurred by them in connection with investigating or defending any
such loss, claim, damage, liability or action; provided, however, that the
indemnity agreement contained in this Section 2.8(a) shall not apply to amounts
paid in settlement of any such loss, claim, damage, liability or action if such
settlement is effected without the consent of the Company, which consent shall
not be unreasonably withheld, nor shall the Company be liable in any such case
for any such loss, claim, damage, liability or action to the extent that it
arises out of or is based upon a Violation which occurs in reliance upon and in
conformity with written information furnished expressly for use in connection
with such registration by such Holder, partner, officer, employee, agent,
director, stockholder, underwriter or controlling Person of such Holder.

                  (b)      To the extent permitted by law, each Holder will
(severally and not jointly), if Registrable Securities held by such Holder are
included in the securities as to which such registration, qualification or
compliance is being effected, indemnify and hold harmless the Company, each of
its directors, its officers, employees, agents and each Person, if any, who
controls the Company within the meaning of the Securities Act, any underwriter
and any other Holder selling securities under such registration statement or any
of such other Holder's partners, directors, officers or stockholders or any
Person who controls such Holder, against any losses, claims, damages or
liabilities to which the Company or any such Person may become subject under the
Securities Act, the Exchange Act or other federal or state law, insofar as such
losses, claims, damages or liabilities (or actions in respect thereto) arise out
of or are based upon any Violation, in each case to the extent (and only to the
extent) that such Violation occurs in reliance upon and in conformity with
written information furnished by such Holder under an

                                     - 11 -
<PAGE>

instrument duly executed by such Holder and stated to be specifically for use in
connection with such registration; and each such Holder will pay as incurred any
legal or other expenses reasonably incurred by the Company or any such Person in
connection with investigating or defending any such loss, claim, damage,
liability or action if it is judicially determined that there was such a
Violation; provided, however, that the indemnity agreement contained in this
Section 2.8(b) shall not apply to amounts paid in settlement of any such loss,
claim, damage, liability or action if such settlement is effected without the
consent of the Holder, which consent shall not be unreasonably withheld;
provided further, that in no event shall any indemnity under this Section 2.8(b)
exceed the net proceeds from the offering actually received by such Holder.

                  (c)      Promptly after receipt by an indemnified party under
this Section 2.8 of notice of the commencement of any action (including any
governmental action), such indemnified party will, if a claim in respect thereof
is to be made against any indemnifying party under this Section 2.8, deliver to
the indemnifying party a written notice of the commencement thereof and
generally summarize such action and the indemnifying party shall have the right
to participate in, and, to the extent the indemnifying party so desires, jointly
with any other indemnifying party similarly noticed, to assume the defense
thereof with counsel mutually satisfactory to the parties; and after notice from
the indemnifying party to such indemnified party of its election so to assume
the defense thereof, the indemnifying party shall not be responsible for any
legal or other expenses subsequently incurred by the indemnified party in
connection with the defense thereof. The failure to deliver written notice to
the indemnifying party within a reasonable time of the commencement of any such
action, if materially prejudicial to its ability to defend such action, shall
relieve such indemnifying party of any liability to the indemnified party under
this Section 2.8, but the omission so to deliver written notice to the
indemnifying party will not relieve it of any liability that it may have to any
indemnified party otherwise than under this Section 2.8. Notwithstanding the
foregoing, if any indemnified party shall have reasonably concluded that there
may be one or more legal or equitable defenses available to such indemnified
party which are in addition to or conflict with those available to the
indemnifying party, or that such claim or litigation involves or could have an
effect upon matters beyond the scope of the indemnity provided in this Section
2.8, the indemnifying party shall not have the right to assume the defense of
such action on behalf of such indemnified party and such indemnifying party
shall reimburse such indemnified party and any Person controlling such
indemnified party for that portion of the fees and expenses of any one lead
counsel (plus appropriate special and local counsel) retained by the indemnified
party which are reasonably related to the matters covered by the indemnity
agreement provided in this Section 2.8.

                  (d)      If the indemnification provided for in this Section
2.8 is held by a court of competent jurisdiction to be unavailable to an
indemnified party with respect to any losses, claims, damages or liabilities
referred to herein, the indemnifying party, in lieu of indemnifying such
indemnified party thereunder, shall to the extent permitted by applicable law
contribute to the amount paid or payable by such indemnified party as a result
of such loss, claim, damage or liability 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 Violation(s) that resulted
in such loss, claim, damage or liability, as well as any other relevant
equitable considerations. The relative fault of the indemnifying party and of
the indemnified party shall be determined by a court of law 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

                                     - 12 -
<PAGE>

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; provided, that in no event shall the maximum
liability in respect of any contribution by a Holder pursuant to this Section
2.8(d) exceed the net proceeds from the offering actually received by such
Holder. No Person guilty of fraudulent misrepresentation (within the meaning of
Section 11(f) of the 1933 Act) shall be entitled to contribution from any Person
who was not guilty of such fraudulent misrepresentation.

                  (e)      The obligations of the Company and Holders under this
Section 2.8 shall survive the transfer of any Registrable Securities or the
completion of any offering of Registrable Securities in a registration statement
and the termination of this Agreement. 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 of a release from all liability in respect
to such claim or litigation.

         2.9      Assignment of Registration Rights. The right to cause the
Company to register Registrable Securities pursuant to this Section 2 may be
assigned by a Holder to a transferee or assignee of Registrable Securities which
(a) is a subsidiary, parent, general partner, limited partner, retired partner,
member, retired member or affiliate of a Holder, (b) is a Holder's spouse or
lineal descendant or trust for the benefit of an individual Holder or his or her
spouse or lineal descendant, (c) acquires at least 50,000 Registrable Securities
(as adjusted for stock splits and combinations) from such Holder, or (d)
acquires Registrable Securities from such Holder without consideration;
provided, that (i) the transferor shall, within twenty (20) days after such
transfer, furnish to the Company written notice of the name and address of such
transferee or assignee and the securities with respect to which such
registration rights are being assigned and (ii) such transferee shall agree to
be subject to all restrictions set forth in this Agreement as evidenced by such
transferee's execution and delivery of an appropriate counterpart signature page
or joinder hereto.

         2.10     Amendment of Registration Rights. Any provision of this
Article 2 may be amended and the observance thereof may be waived (either
generally or in a particular instance and either retroactively or
prospectively), only with the written consent of the Company and the Holders of
two-thirds (2/3) of the Registrable Securities then outstanding; provided,
however, that any such amendment, modification, or waiver that would adversely
affect the rights hereunder of an Investor, in its capacity as an Investor,
without similarly affecting the rights hereunder of all Investors of such class,
in their capacities as Investors of such class, shall not be effective as to
such Investor without its prior written consent. Any amendment or waiver
effected in accordance with this Section 2.10 shall be binding upon each Holder
and the Company. By acceptance of any benefits under this Article 2, Holders
hereby agree to be bound by the provisions hereunder.

         2.11     Limitation on Subsequent Registration Rights. After the date
of this Agreement, the Company shall not, without the prior written consent of
the Holders of at least two-thirds (2/3) of the Registrable Securities then
outstanding, enter into any agreement with any holder or prospective holder of
any securities of the Company that would grant such holder registration

                                     - 13 -
<PAGE>

rights on parity with or senior to those granted to the Holders hereunder or
which rights could be reasonably expected to conflict with the rights granted to
the Holders hereunder.

         2.12     "Market Stand-Off" Agreement; Agreement to Furnish
Information. Each Holder hereby agrees that such Holder shall not sell or
otherwise transfer or dispose of any Common Stock (or other securities) of the
Company held by such Holder (other than those included in the registration) for
a period specified by the representative of the underwriters of Common Stock (or
other securities) of the Company not to exceed ninety (90) days or, in the case
of the Initial Public Offering, one hundred eighty (180) days following the
effective date of a registration statement of the Company filed under the
Securities Act (the "Lock-up"); provided that:

                  (a)      such agreement shall apply only to a secondary public
offering in which such Holder is participating or to the Initial Public
Offering;

                  (b)      with respect to the Initial Public Offering, all (A)
officers and directors of the Company and (B) all stockholders of the Company
that own at least one-half percent (0.5%) of the Company's Common Stock (on an
as converted basis) enter into similar agreements and with respect to a
secondary public offering, all (X) officers and directors of the Company and (Y)
Holders selling shares in such offering enter into similar agreements; provided,
that if all such Persons are not subject to the Lock-up, the shares of Common
Stock that are subject to the Lock-up shall first be shares of Common Stock and
then shares of Series A Preferred Stock, Series B Preferred Stock and Series C
Preferred Stock (allocated amongst the Company's stockholders on a pro rata
basis); and

                  (c)      any amendment or modification that benefits any
stockholder or any termination, in either case with regard to the terms of any
Lock-up to which any stockholder of the Company is subject, shall similarly
affect the rights of all Holders.

         Each Holder participating in the applicable registration agrees to
execute and deliver such other agreements as may be reasonably requested by the
Company or the underwriter which are consistent with the foregoing or which are
necessary to give further effect thereto. In addition, if requested by the
Company or the representative of the underwriters of Common Stock (or other
securities) of the Company, each Holder participating in the applicable
registration shall provide, as soon as practicable after receipt of such
request, such information as may be reasonably required by the Company or such
representative in connection with the completion of any public offering of the
Company's securities pursuant to a registration statement filed under the
Securities Act. The obligations described in this Section 2.12 shall not apply
to a registration relating solely to employee benefit plans on Form S-1 or Form
S-8 or similar forms that may be promulgated in the future, or a registration
relating solely to a Commission Rule 145 transaction on Form S-4 or similar
forms that may be promulgated in the future. The Company may impose
stop-transfer instructions with respect to the shares of Common Stock (or other
securities) subject to the foregoing restriction until the end of said ninety
(90) day or one-hundred eighty (180) day period.

         2.13     Rule 144 Reporting. With a view to making available to the
Holders the benefits of certain rules and regulations of the SEC which may
permit the sale of the Registrable Securities to the public without
registration, the Company agrees to use its best efforts to:

                                     - 14 -
<PAGE>

                  (a)      Make and keep public information available, as those
terms are understood and defined in SEC Rule 144 or any similar or analogous
rule promulgated under the Securities Act, at all times after the effective date
of the first registration filed by the Company for an offering of its securities
to the general public;

                  (b)      File with the SEC, in a timely manner, all reports
and other documents required of the Company under the Exchange Act; and

                  (c)      So long as a Holder owns any Registrable Securities,
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 of
the Securities Act, and of the 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 as a
Holder may reasonably request in availing itself of any rule or regulation of
the SEC allowing it to sell any such securities without registration.

                  (d)      Termination of Registration Rights. No Holder shall
be entitled to exercise any right provided for in this Article 2 after such time
as all such Holder's Registrable Securities may be sold in a single sale without
regard to any volume limitations pursuant to Rule 144.

                                   ARTICLE 3

                                 MISCELLANEOUS

         3.1      Governing Law. This Agreement shall be governed by and
construed under the laws of the State of Delaware, without applying conflicts of
law principles.

         3.2      Jurisdiction. The parties hereto agree that any suit, action
or proceeding instituted against one or more of them with respect to this
Agreement (including any exhibits hereto) may be brought in any federal or state
court located in the State of New York. The parties hereto, by the execution and
delivery of this Agreement, irrevocably waive any obligation or any right of
immunity on the ground of venue, the convenience of the forum or the
jurisdiction of such courts, or from the execution of judgments resulting
therefrom, and the parties hereto irrevocably accept and submit to the
jurisdiction of the aforesaid courts in any suit, action or proceeding and
consent to the service of process by certified mail at the respective address of
the Company set forth on the signature pages hereof and of the Investors set
forth on Exhibit A or such other address as such party shall have designated in
writing to the other parties hereto.

         EACH OF THE PARTIES HERETO IRREVOCABLY WAIVES ALL RIGHT TO TRIAL BY
JURY IN ANY ACTION, PROCEEDING OR COUNTERCLAIM ARISING OUT OF OR RELATING TO
THIS AGREEMENT.

         3.3      Survival. The representations, warranties, covenants, and
agreements made herein shall survive any investigation made by any Investor and
the closing of the transactions contemplated hereby. All statements as to
factual matters contained in any certificate or other instrument delivered by or
on behalf of the Company pursuant hereto in connection with the

                                     - 15 -
<PAGE>

transactions contemplated hereby shall be deemed to be representations and
warranties by the Company hereunder solely as of the date of such certificate or
instrument.

         3.4      Successors and Assigns. Except as otherwise expressly 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 and shall inure to the benefit of and be enforceable by each
Person who shall be a holder of Registrable Securities from time to time;
provided, however, that prior to the receipt by the Company of adequate written
notice of the transfer of any Registrable Securities specifying the full name
and address of the transferee, the Company may deem and treat the Person listed
as the holder of such shares in its records as the absolute owner and holder of
such shares for all purposes, including the payment of dividends or any
redemption price.

         3.5      Entire Agreement. This Agreement, the Series C Securities
Acquisition Agreement and the Exhibits thereto and the Stockholders Agreement
and the other documents delivered pursuant hereto embodies the entire agreement
and understanding between the parties hereto with respect to the understanding
and agreement between the parties with regard to the subjects hereof and
supersedes all prior agreements and understandings relating to such subject
matter.

         3.6      Severability. It is the desire and intent of the parties
hereto that the provisions of this Agreement be enforced to the fullest extent
permissible under the laws and public policies applied in each jurisdiction in
which enforcement is sought. Accordingly, in case any provision of the Agreement
shall be adjudicated by a court of competent jurisdiction to be invalid,
illegal, or unenforceable, such provision, as to such jurisdiction, shall be
ineffective, without affecting the validity, legality, and enforceability of the
remaining provisions of this Agreement or affecting the validity or
enforceability of such provision in any other jurisdiction.

         3.7      Amendment and Waiver.

                  (a)      Except as otherwise expressly provided, including in
Section 2.10 above, this Agreement may be amended or modified only upon the
consent of the Company and the holders of a majority of the Registrable
Securities; provided, however, that any such amendment, modification, or waiver
that would adversely affect the rights hereunder of any Investor, in its
capacity as an Investor, without similarly affecting the rights hereunder of all
Investors of such class, in their capacities as Investors of such class, shall
not be effective as to such Investor without its prior written consent.

                  (b)      Except as otherwise expressly provided, the
obligations of the Company under this Agreement may be waived only with the
consent of the holders of a majority of the Registrable Securities.

         3.8      Delays or Omissions. It is agreed that no delay or omission to
exercise any right, power, or remedy accruing to any Holder, upon any breach,
default or noncompliance of the Company under this Agreement shall impair any
such right, power, or remedy, nor shall it be construed to be a waiver of any
such breach, default or noncompliance, or any acquiescence therein, or of any
similar breach, default or noncompliance thereafter occurring. It is further

                                     - 16 -
<PAGE>

agreed that any waiver, permit, consent, or approval of any kind or character on
any Holder's part of any breach, default or noncompliance under the Agreement or
any waiver on such Holder's part of any provisions or conditions of this
Agreement must be in writing and shall be effective only to the extent
specifically set forth in such writing. All remedies, either under this
Agreement, by law, or otherwise afforded to Holders, shall be cumulative and not
alternative.

         3.9      Notices. All notices and consents required or permitted
hereunder must be in writing and shall be deemed effectively given: (a) upon
personal delivery to the party to be notified, (b) when sent by confirmed
facsimile upon receipt, (c) three business days after having been sent by
registered or certified mail, return receipt requested, postage prepaid, or (d)
one business day after deposit with a nationally recognized overnight courier,
specifying next day delivery, with written verification of receipt. All
communications shall be sent to the party to be notified at the respective
address of the Company set forth on the signature pages hereof and of the
Investors set forth on Exhibit A or at such other address as such party may
designate in writing to the other parties hereto.

         3.10     Headings. The headings of the sections, subsections, and
paragraphs of this Agreement have been added for convenience only and shall not
be deemed to be a part of this Agreement.

         3.11     Counterparts. This Agreement may be executed in any number of
counterparts, each of which shall be an original, but all of which together
shall constitute one instrument.

                            [SIGNATURE PAGES FOLLOW]

                                     - 17 -
<PAGE>

                  IN WITNESS WHEREOF, the parties hereto have executed this
Investor Rights Agreement as of the date first above written.

                               COMPANY:

                               BARRIER THERAPEUTICS, INC.

                                   GEERT CAUWENBERGH
                               By: _____________________________________________
                                   Geert Cauwenbergh
                                   Chief Executive Officer

                               Address:  600 College Road East
                                         Suite 3200
                                         Princeton, NJ 08540

                               INVESTOR:

                               MPM BIOVENTURES III, L.P.
                               By: MPM BioVentures III GP, L.P.,
                                     its General Partner
                               By: MPM BioVentures III LLC, its General Partner

                                   NICHOLAS J. SIMON III
                               By: _____________________________________________
                               Name: Nicholas J. Simon III
                               Title: Series A Member

                               MPM BIOVENTURES III-QP, L.P.
                               By: MPM BioVentures III GP, L.P.,
                                     its General Partner
                               By: MPM BioVentures III LLC, its General Partner

                                   NICHOLAS J. SIMON III
                               By: _____________________________________________
                               Name: Nicholas J. Simon III
                               Title: Series A Member

                               MPM BIOVENTURES III Parallel Fund, L.P.
                               By: MPM BioVentures III GP, L.P.,
                                     its General Partner
                               By: MPM BioVentures III LLC, its General Partner

                                   NICHOLAS J. SIMON III
                               By: _____________________________________________
                               Name: Nicholas J. Simon III
                               Title: Series A Member

       [SIGNATURE PAGE TO AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT]

<PAGE>

                               MPM BIOVENTURES III GMBH & CO.
                               BETEILIGUNGS KG
                               By: MPM BioVentures III GP, L.P., in its capacity
                                     as the Managing Limited Partner
                               By: MPM BioVentures III LLC, its General Partner

                                   NICHOLAS J. SIMON III
                               By: _____________________________________________
                               Name: Nicholas J. Simon III
                               Title: Series A Member

                               MPM ASSET MANAGEMENT INVESTORS 2003 BVIII LLC

                                   NICHOLAS J. SIMON III
                               By: _____________________________________________
                               Name: Nicholas J. Simon III
                               Title: Manager

                               MPM BIOEQUITIES FUND GMBH & CO. KG

                               By: MPM BioEquities GP, L.P., in its capacity
                                   as the Managing Limited Partner

                               By: MPM BioEquities GP LLC,
                                   its General Partner

                                   ROBERT W. LIPTAK
                               By: _____________________________________________
                                   Robert W. Liptak
                                   Manager

                               MPM BIOEQUITIES MASTER FUND, LP

                               By: MPM BioEquities GP, L.P.,
                                   its General Partner

                               By: MPM BioEquities GP LLC,
                                   its General Partner

                                   ROBERT W. LIPTAK
                               By: _____________________________________________
                                   Robert W. Liptak
                                   Manager

       [SIGNATURE PAGE TO AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT]

<PAGE>

                               J.P. MORGAN PARTNERS (BHCA), L.P.

                               By: JPMP Master Fund Manager, L.P.,
                                   its general partner

                               By: JPMP Capital Corp.,
                                   its general partner

                               By: DAMION E. WICKER
                                   _____________________________________________
                                   Name:  Damion E. Wicker, M.D.
                                   Title: Partner

                               J.P. MORGAN PARTNERS GLOBAL INVESTORS, L.P.,

                               By: JPMP Global Investors, L.P.,
                                   its general partner

                               By: JPMP Capital Corp.,
                                   its general partner

                               By: DAMION E. WICKER
                                   _____________________________________________
                                   Name:  Damion E. Wicker, M.D.
                                   Title: Partner

                               J.P. MORGAN PARTNERS GLOBAL INVESTORS (CAYMAN),
                               L.P.

                               By: JPMP Global Investors, L.P.,
                                   its general partner

                               By: JPMP Capital Corp.,
                                   its general partner

                               By: DAMION E. WICKER
                                   _____________________________________________
                                   Name:  Damion E. Wicker, M.D.
                                   Title: Partner

       [SIGNATURE PAGE TO AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT]

<PAGE>

                               J.P. MORGAN PARTNERS GLOBAL INVESTORS A, L.P.

                               By: JPMP Global Investors, L.P.,
                                   its general partner

                               By: JPMP Capital Corp.,
                                   its general partner

                               By: DAMION E. WICKER
                                   _____________________________________________
                                   Name:  Damion E. Wicker, M.D.
                                   Title: Partner

                               J.P. MORGAN PARTNERS GLOBAL INVESTORS (CAYMAN)
                               II, L.P.

                               By: JPMP Global Investors, L.P.,
                                   its general partner

                               By: JPMP Capital Corp.,
                                   its general partner

                               By: DAMION E. WICKER
                                   _____________________________________________
                                   Name:  Damion E. Wicker, M.D.
                                   Title: Partner

       [SIGNATURE PAGE TO AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT]

<PAGE>

                               TL VENTURES V L.P.

                               By: TL Ventures V Management L.P.,
                                   its general partner

                               By: TL Ventures V LLC,
                                   its manager

                               By: PAMELA A. STRISOFSKY
                                   _____________________________________________
                                   Name:   Pamela A. Strisofsky
                                   Title:  Chief Financial Officer

                               TL VENTURES V INTERFUND L.P.

                               By: TL Ventures V LLC,
                                   its general partner

                               By: PAMELA A. STRISOFSKY
                                   _____________________________________________
                                   Name:  Pamela A. Strisofsky
                                   Title: Chief Financial Officer

       [SIGNATURE PAGE TO AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT]

<PAGE>

                               KBC PRIVATE EQUITY FUND BIOTECH NV

                               By: RUTH DEVENYNS
                                   _____________________________________________
                                   Name:  Ruth Devenyns
                                   Title: Senior Investment Manager

                               KBC EQUITY FUND NV

                               By: RUTH DEVENYNS
                                   _____________________________________________
                                   Name:  Ruth Devenyns
                                   Title: Senior Investment Manager

                               KBC EQUITY FUND BIOTECHNOLOGY

                               By: RUTH DEVENYNS
                                   _____________________________________________
                                   Name:  Ruth Devenyns
                                   Title: Senior Investment Manager

                               KBC EQUITY FUND PHARMA

                               By: RUTH DEVENYNS
                                   _____________________________________________
                                   Name:  Ruth Devenyns
                                   Title: Senior Investment Manager

       [SIGNATURE PAGE TO AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT]

<PAGE>

                               PERSEUS-SOROS BIOPHARMACEUTICAL FUND, LP

                               By: ILLEGIBLE
                               _________________________________________________
                               Name:
                               Title: Attorney-in-Fact

       [SIGNATURE PAGE TO AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT]

<PAGE>

                               BAKER/TISCH INVESTMENTS, L.P.

                               By: Baker/Tisch Capital, L.P.,
                                   its general partner
                               By: Baker/Tisch Capital (GP), LLC,
                                   its general partner

                               By: FELIX BAKER
                                   _____________________________________________
                                   Felix Baker
                                   Managing Member

                               BAKER BROS. INVESTMENTS, L.P.

                               By: Baker Bros. Capital, L.P.,
                                   its general partner
                               By: Baker Bros. Capital (GP), LLC,
                                   its general partner

                               By: FELIX BAKER
                                   _____________________________________________
                                   Felix Baker
                                   Managing Member

                               BAKER BROS. INVESTMENTS II, L.P.

                               By: Baker Bros. Capital, L.P.,
                                   its general partner
                               By: Baker Bros. Capital (GP), LLC,
                                   its general partner

                               By: FELIX BAKER
                                   _____________________________________________
                                   Felix Baker
                                   Managing Member

       [SIGNATURE PAGE TO AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT]

<PAGE>

                               BAKER BIOTECH FUND I, L.P.

                               By: Baker Biotech Capital, L.P.,
                                   its general partner
                               By: Baker Biotech Capital (GP), LLC,
                                   its general partner

                               By: FELIX BAKER
                                   _____________________________________________
                                   Felix Baker
                                   Managing Member

                               BAKER BIOTECH FUND II, L.P.

                               By: Baker Biotech Capital II, L.P.,
                                   its general partner
                               By: Baker Biotech Capital II (GP), LLC,
                                   is general partner

                               By: FELIX BAKER
                                   _____________________________________________
                                   Felix Baker
                                   Managing Member

       [SIGNATURE PAGE TO AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT]

<PAGE>

                               JOHNSON & JOHNSON DEVELOPMENT CORPORATION

                               By: TING PAU OEI
                                   _____________________________________________
                                   Ting Pau Oei
                                   Vice President

                               JANSSEN PHARMACEUTICA PRODUCTS, L.P.

                               By: Janssen Pharmaceutica Inc.,
                                   its general partner

                               By: PETER K. MILLER
                                   _____________________________________________
                                   Name: Peter K. Miller
                                   Title: President

                               JOHNSON & JOHNSON CONSUMER COMPANIES, INC.

                               By: CLAYTON H. PATERSON
                                   _____________________________________________
                                   Name: Clayton H. Paterson
                                   Title: Secretary

       [SIGNATURE PAGE TO AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT]

<PAGE>

                                                                       EXHIBIT A

                                LIST OF INVESTORS

MPM BioVentures III, L.P.
MPM BioVentures III-QP, L.P.
MPM BioVentures III Parallel Fund, L.P.
MPM BioVentures III GMBH & Co. BETEILIGUNGS KG
MPM Asset Management Investors 2003 BVIII LLC
MPM BioEquities Fund GMBH & Co. KG, and
MPM BioEquities Master Fund, LP

Address:

                  111 Huntington Avenue
                  31st Floor
                  Boston, MA 02199
                  Facsimile: 617.425.9200
                  Attention: William Greene

              with a copy to:

                  Cooley Godward LLP
                  Five Palo Alto Square
                  3000 El Camino Real
                  Palo Alto, CA 94306-2155
                  Facsimile: 650.849.7400
                  Attention: James Kitch

J.P. Morgan Partners (BHCA), L.P.
Address:

                  1221 Avenue of the Americas
                  New York, NY 10020
                  Facsimile: (212) 899-3401
                  Attention: Official Notices Clerk
                  (fbo Srinivas Akkaraju)

              with a copy to:

                  O'Melveny & Myers LLP
                  30 Rockefeller Plaza
                  New York, NY 10112
                  Facsimile: (212) 728-5950
                  Attention: Phillip Isom, Esq.

                                       A-1
<PAGE>

J.P. Morgan Partners Global Investors, L.P.
Address:

                  1221 Avenue of the Americas
                  New York, NY 10020
                  Facsimile: (212) 899-3401
                  Attention: Official Notices Clerk
                  (fbo Srinivas Akkaraju)

              with a copy to:

                  O'Melveny & Myers LLP
                  30 Rockefeller Plaza
                  New York, NY 10112
                  Facsimile: (212) 728-5950
                  Attention: Phillip Isom, Esq.

J.P. Morgan Partners Global Investors (Cayman), L.P.
Address:

                  1221 Avenue of the Americas
                  New York, NY 10020
                  Facsimile: (212) 899-3401
                  Attention: Official Notices Clerk
                  (fbo Srinivas Akkaraju)

              with a copy to:

                  O'Melveny & Myers LLP
                  30 Rockefeller Plaza
                  New York, NY 10112
                  Facsimile: (212) 728-5950
                  Attention: Phillip Isom, Esq.

                                       A-2
<PAGE>

J.P. Morgan Partners Global Investors A, L.P.
Address:

                  1221 Avenue of the Americas
                  New York, NY 10020
                  Facsimile: (212) 899-3401
                  Attention: Official Notices Clerk
                  (fbo Srinivas Akkaraju)

              with a copy to:

                  O'Melveny & Myers LLP
                  30 Rockefeller Plaza
                  New York, NY 10112
                  Facsimile: (212) 728-5950
                  Attention: Phillip Isom, Esq.

J.P. Morgan Partners Global Investors (Cayman) II, L.P.
Address:

                  1221 Avenue of the Americas
                  New York, NY 10020
                  Facsimile: (212) 899-3401
                  Attention: Official Notices Clerk
                  (fbo Srinivas Akkaraju)

              with a copy to:

                  O'Melveny & Myers LLP
                  30 Rockefeller Plaza
                  New York, NY 10112
                  Facsimile: (212) 728-5950
                  Attention: Phillip Isom, Esq.

                                       A-3
<PAGE>

TL Ventures V L.P.
Address:

                  700 Building
                  435 Devon Park Drive
                  Wayne, PA 19087
                  Facsimile: (610) 975-9330
                  Attention: Devang V. Kantesaria

              with a copy to:

                  Dechert
                  Princeton Pike Corporate Center
                  997 Lenox Drive
                  Building 3, Suite 210
                  Lawrenceville, NJ 08648
                  Facsimile: (609) 620-3259
                  Attention: James J. Marino, Esq.

TL Ventures V Interfund L.P.
Address:

                  700 Building
                  435 Devon Park Drive
                  Wayne, PA 19087
                  Facsimile: (610) 975-9330
                  Attention: Devang V. Kantesaria

              with a copy to:

                  Dechert
                  Princeton Pike Corporate Center
                  997 Lenox Drive
                  Building 3, Suite 210
                  Lawrenceville, NJ 08648
                  Facsimile: (609) 620-3259
                  Attention: James J. Marino, Esq.

                                       A-4
<PAGE>

KBC Private Equity Fund Biotech NV
Address:          ALA
                  Havenlaan 2
                  1080 Brussels
                  BELGIUM
                  Facsimile: 32 2 429 59 29
                  Attention: Jo Vander Stuyft, Secretary of the Board

              with a copy to:

                  KBC Private Equity Fund Biotech NV
                  Havenlaan 12
                  1080 Brussels
                  BELGIUM
                  Facsimile: 32 2 429 05 25
                  Attention: Ruth Devenyns, Attorney in fact

KBC Equity Fund NV
Address:          ALA
                  Havenlaan 2
                  1080 Brussels
                  BELGIUM
                  Facsimile:32 2 429 59 29
                  Attention: Jo Vander Stuyft, Legal Adviser

              with a copy to:

                  KBC Equity Fund NV
                  Havenlaan 12
                  1080 Brussels
                  BELGIUM
                  Facsimile: 32 2 429 05 25
                  Attention: Ruth Devenyns, Attorney in fact

                                       A-5
<PAGE>

KBC Equity Fund Biotechnology
Address:          ALA
                  Havenlaan 2
                  1080 Brussels
                  BELGIUM
                  Facsimile: 32 2 429 59 29
                  Attention: Jo Vander Stuyft, Legal Adviser

              with a copy to:

                  KBC Equity Fund Biotechnology
                  Havenlaan 12
                  1080 Brussels
                  BELGIUM
                  Facsimile: 32 2 429 05 25
                  Attention: Ruth Devenyns, Attorney in fact

KBC Equity Fund Pharma
Address:          ALA
                  Havenlaan 2
                  1080 Brussels
                  BELGIUM
                  Facsimile: 32 2 429 59 29
                  Attention: Jo Vander Stuyft, Legal Adviser

              with a copy to:

                  KBC Equity Fund Pharma
                  Havenlaan 12
                  1080 Brussels
                  BELGIUM
                  Facsimile: 32 2 429 05 25
                  Attention: Ruth Devenyns, Attorney in fact

                                       A-6
<PAGE>

Perseus-Soros Biopharmaceutical Fund, L.P.
Address:          888 Seventh Avenue, 29th Floor
                  New York, NY 10106
                  Facsimile: (212) 651-6379
                  Attention: Dr. Andrew Schiff

              with a copy to:

                  Perseus-Soros Biopharmaceutical Fund, L.P.
                  c/o Soros Fund Management LLC
                  888 Seventh Avenue, 31st Floor
                  New York, NY 10106
                  Attention: Richard D. Holahan, Jr., Esq.

                  and

                  Paul, Weiss, Rifkind, Wharton & Garrison, LLP
                  1285 Avenue of the Americas
                  New York, NY 10019-6064
                  Facsimile: (212) 757-3990
                  Attention: Bruce A. Gutenplan, Esq.

Baker/Tisch Investments, L.P.
Address:          655 Madison Avenue, 19th Floor
                  New York, New York 10021
                  Facsimile: (212) 521-2245
                  Attention: Felix Baker

              with a copy to:

                  Baker Brothers Investments
                  655 Madison Avenue, 19th Floor
                  New York, New York 10021
                  Facsimile: (212) 521-2245
                  Attention: Leo Kirby

                                       A-7
<PAGE>

Baker Bros. Investments, L.P.
Address:          655 Madison Avenue, 19th Floor
                  New York, New York 10021
                  Facsimile: (212) 521-2245
                  Attention: Felix Baker

              with a copy to:

                  Baker Brothers Investments
                  655 Madison Avenue, 19th Floor
                  New York, New York 10021
                  Facsimile: (212) 521-2245
                  Attention: Leo Kirby

Baker Bros. Investments II, L.P.
Address:          655 Madison Avenue, 19th Floor
                  New York, New York 10021
                  Facsimile: (212) 521-2245
                  Attention: Felix Baker

              with a copy to:

                  Baker Brothers Investments
                  655 Madison Avenue, 19th Floor
                  New York, New York 10021
                  Facsimile: (212) 521-2245
                  Attention: Leo Kirby

Baker Biotech Fund I, L.P.
Address:          655 Madison Avenue, 19th Floor
                  New York, New York 10021
                  Facsimile: (212) 521-2245
                  Attention: Felix Baker

              with a copy to:

                  Baker Brothers Investments
                  655 Madison Avenue, 19th Floor
                  New York, New York 10021
                  Facsimile: (212) 521-2245
                  Attention: Leo Kirby

                                       A-8
<PAGE>

Baker Biotech Fund II, L.P.
Address:          655 Madison Avenue, 19th Floor
                  New York, New York 10021
                  Facsimile: (212) 521-2245
                  Attention: Felix Baker

              with a copy to:

                  Baker Brothers Investments
                  655 Madison Avenue, 19th Floor
                  New York, New York 10021
                  Facsimile: (212) 521-2245
                  Attention: Leo Kirby

Johnson & Johnson Consumer Companies, Inc.
Address:          c/o Johnson & Johnson Development Corporation
                  1 Johnson & Johnson Plaza
                  New Brunswick, NJ 08933
                  Facsimile: (732) 247-5309
                  Attention: Ting Pau Oei

              with a copy to:

                  Johnson & Johnson Law Department
                  1 Johnson & Johnson Plaza
                  New Brunswick, NJ 08933
                  Facsimile: (732) 524-2788
                  Attention: Sheldon Hirt

Janssen Pharmaceutica Products, L.P.
Address:          c/o Johnson & Johnson Development Corporation
                  1 Johnson & Johnson Plaza
                  New Brunswick, NJ 08933
                  Facsimile: (732) 247-5309
                  Attention: Ting Pau Oei

              with a copy to:

                  Johnson & Johnson Law Department
                  1 Johnson & Johnson Plaza
                  New Brunswick, NJ 08933
                  Facsimile: (732) 524-2788
                  Attention: Sheldon Hirt

                                       A-9
<PAGE>

Johnson & Johnson Development Corporation
Address:          1 Johnson & Johnson Plaza
                  New Brunswick, NJ 08933
                  Facsimile: (732) 247-5309
                  Attention: Ting Pau Oei

              with a copy to:

                  Johnson & Johnson Law Department
                  1 Johnson & Johnson Plaza
                  New Brunswick, NJ 08933
                  Facsimile: (732) 524-2788
                  Attention: Sheldon Hirt

                                      A-10