FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * MPM BioVentures IV QP LP   2. Issuer Name and Ticker or Trading Symbol PEPLIN INC [PLIN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director __X__ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O MPM ASSET MANAGEMENT, 200 CLARENDON STREET, 54TH FLOOR 3. Date of Earliest Transaction (Month/Day/Year) 02/10/2009 (Street) BOSTON, MA 02116 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) ___ Form filed by One Reporting Person _X_ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 02/11/2009   P   999 (1) (2) A $ 8 3,417,807 I See Footnote (3) Common Stock 02/12/2009   P   1,249 (1) (4) A $ 8.2 3,419,056 I See Footnote (5)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
MPM BioVentures IV QP LP C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116		X
MPM BioVentures IV GP LLC C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116		X
MPM BioVentures IV LLC C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116		X
MPM Asset Management Investors BV4 LLC C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116		X
MPM BioVentures IV GmbH & Co. Beteiligungs KG C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116		X
MPM BIOVENTURES III GP LP C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116		X
MPM BIOVENTURES III LLC C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116		X
MPM BIOVENTURES III LP C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116		X
MPM BIOVENTURES III QP LP C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116		X
MPM BIOVENTURES III GMBH & CO. Beteiligungs KG C/O MPM ASSET MANAGEMENT 200 CLARENDON STREET, 54TH FLOOR BOSTON, MA 02116		X

Signatures

By Vaughn Kailian, member of MPM BioVentures IV LLC, the managing member of MPM BioVentures IV GP LLC, the general partner of MPM BioVentures IV-QP, L.P. /s/ Vaughn Kailian		02/12/2009
**Signature of Reporting Person		Date
By Vaughn Kailian, member of MPM BioVentures IV LLC, the managing member of MPM BioVentures IV GP LLC /s/ Vaughn Kailian		02/12/2009
**Signature of Reporting Person		Date
By Vaughn Kailian, member of MPM BioVentures IV LLC /s/ Vaughn Kailian		02/12/2009
**Signature of Reporting Person		Date
By Vaughn Kailian, member of MPM BioVentures IV LLC, the manager of MPM Asset Management Investors BV4 LLC /s/ Vaughn Kailian		02/12/2009
**Signature of Reporting Person		Date
By Vaughn M. Kailian, member of MPM BioVentures IV LLC, the managing member of MPM BioVentures IV GP LLC, the managing limited partner of MPM BioVentures IV GmbH & Co. Beteiligungs KG /s/ Vaughn M. Kailian		02/12/2009
**Signature of Reporting Person		Date
By Luke Evnin, Series A Member of MPM BioVentures III LLC, the general partner of MPM BioVentures III GP, LP /s/ Luke Evnin		02/12/2009
**Signature of Reporting Person		Date
By Luke Evnin, Series A Member of MPM BioVentures III LLC /s/ Luke Evnin		02/12/2009
**Signature of Reporting Person		Date
By Luke Evnin, Series A Member of MPM BioVentures III LLC, the general partner of MPM BioVentures III GP, LP, the general partner of MPM BioVentures III, LP /s/ Luke Evnin		02/12/2009
**Signature of Reporting Person		Date
By Luke Evnin, Series A Member of MPM BioVentures III LLC, the general partner of MPM BioVentures III GP, LP, the general partner of MPM BioVentures III-QP, LP /s/ Luke Evnin		02/12/2009
**Signature of Reporting Person		Date
By Luke Evnin, Series A Member of MPM BioVentures III LLC, the general partner of MPM BioVentures III GP, LP, in its capacity as the Managing Limited Partner of MPM BioVentures III GmbH & Co. Beteiligungs KG /s/ Luke Evnin		02/12/2009
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	Represents shares of Common Stock underlingy CHESS Depository Interests ("CDIs") acquired by the reporting persons. CDIs are units of beneficial ownership in shares of Common Stock held by CHESS Depositary Nominees Pty Limited, a wholly-owned subsidiary of the Australian Stock Exchange. The CDIs are economically equivalent to shares of Common Stock of the Issuer on a 1-for-20 basis.
(2)	The Common Stock equivalent of CDIs were purchased as follows: 937 by MPM BioVentures IV-QP, L.P. ("BV IV QP"), 36 by MPM BioVentures IV GmbH & Co. Beteiligungs KG ("BV IV KG") and 26 by MPM Asset Management Investors BV4 LLC ("AM BV4"). Excludes fractional shares that result from the conversion of CDIs. MPM BioVentures IV GP LLC and MPM BioVentures IV LLC are the direct and indirect general partners of BV IV QP, BV IV KG and AM BV4. Vaughn M. Kailian, Ansbert Gadicke, Luke Evnin, Steven St. Peter, William Greene, James Paul Scopa, Ashley Dombkowski and John Vander Vort are the members of the general partner of BV IV QP, BV IV KG and members of AM BV4. MPM BioVentures III GP, L.P. ("BV III GP") and MPM BioVentures III LLC ("BV III LLC") are the direct and indirect general partners of MPM BioVentures III, LP. ("BV III"), MPM BioVentures III-QP, LP ("BV III QP"), MPM BioVentures III Parallel Fund, LP ("BV III PF"), MPM BioVentures III GmbH & Co. Beteiligungs KG ("BV III KG") and MPM BioVentures Strategic Fund, LP ("BV SF"). Luke Evnin and Ansbert Gadicke are Series A members of BV III LLC and managers of AM BV III. Each member of the group disclaims beneficial ownership of the securities except to the extent of his, her or its respective pecuniary interest therein.
(3)	Shares of Common Stock, which include shares underlying CDIs are held as follows: 2,716,144 by BV IV QP, 104,635 by BV IV KG, 77,228 by AM BV4, 25,510 by BV III, 379,381 by BV III QP, 32,061 by BV III KG, 11,456 by BV III PF, 9,017 by AM BV III and 62,375 by BV SF. Each member of the group disclaims beneficial ownership of the securities except to the extent of his, her or its respective pecuniary interest therein.
(4)	The Common Stock equivalent of CDIs were purchased as follows: 1,171 by BV IV QP, 45 by BV IV KG and 33 by AM BV4. Excludes fractional shares that result from the conversion of CDIs. Each member of the group disclaims beneficial ownership of the securities except to the extent of his, her or its respective pecuniary interest therein.
(5)	Shares of Common Stock, which include shares underlying CDIs are held as follows: 2,717,315 by BV IV QP, 104,680 by BV IV KG, 77,261 by AM BV4, 25,510 by BV III, 379,381 by BV III QP, 32,061 by BV III KG, 11,456 by BV III PF, 9,017 by AM BV III and 62,375 by BV SF. Each member of the group disclaims beneficial ownership of the securities except to the extent of his, her or its respective pecuniary interest therein.
Remarks: See Form 4 for Vaughan Kailian for additional members of this joint filing.

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