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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934
(Amendment No. 2)*

METABASIS THERAPEUTICS, INC.
(Name of Issuer)
Common Stock
(Title of Class of Securities)
59101M 10 5
(CUSIP Number)
December 31, 2006
(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

     o Rule 13d-1(b)

     o Rule 13d-1(c)

     þ Rule 13d-1(d)

* The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

 
 

 

                     
CUSIP No.
  
59101M 10 5 
                

 

           
1   NAMES OF REPORTING PERSONS:
InterWest Partners VII, LP
   
  I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY): 
   
     
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):
  (a)   o
  (b)   o
     
3   SEC USE ONLY:
   
   
     
4   CITIZENSHIP OR PLACE OF ORGANIZATION:
   
  California
       
  5   SOLE VOTING POWER:
     
NUMBER OF   3,040,686
       
SHARES 6   SHARED VOTING POWER:
BENEFICIALLY    
OWNED BY   0
       
EACH 7   SOLE DISPOSITIVE POWER:
REPORTING    
PERSON   3,040,686
       
WITH: 8   SHARED DISPOSITIVE POWER:
     
    0
     
9   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:
   
  3,040,686
     
10   CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):
   
  o
     
11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9):
   
  10.0%
     
12   TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):
   
  PN

Page 2 of 16 Pages

 

                     
CUSIP No.
  
59101M 10 5 
                

 

           
1   NAMES OF REPORTING PERSONS:
InterWest Investors VII, LP
   
  I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY): 
   
     
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):
  (a)   o
  (b)   o
     
3   SEC USE ONLY:
   
   
     
4   CITIZENSHIP OR PLACE OF ORGANIZATION:
   
  California
       
  5   SOLE VOTING POWER:
     
NUMBER OF   145,612
       
SHARES 6   SHARED VOTING POWER:
BENEFICIALLY    
OWNED BY   0
       
EACH 7   SOLE DISPOSITIVE POWER:
REPORTING    
PERSON   145,612
       
WITH: 8   SHARED DISPOSITIVE POWER:
     
    0
     
9   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:
   
  145,612
     
10   CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):
   
  o
     
11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9):
   
  0.5%
     
12   TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):
   
  PN

Page 3 of 16 Pages

 

                     
CUSIP No.
  
59101M 10 5 
                

 

           
1   NAMES OF REPORTING PERSONS:
InterWest Management Partners VII, LLC (the General Partner of InterWest Partners VII, LP and InterWest Investors VII, LP)
   
  I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY): 
   
     
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):
  (a)   o
  (b)   o
     
3   SEC USE ONLY:
   
   
     
4   CITIZENSHIP OR PLACE OF ORGANIZATION:
   
  California
       
  5   SOLE VOTING POWER:
     
NUMBER OF   3,186,298
       
SHARES 6   SHARED VOTING POWER:
BENEFICIALLY    
OWNED BY   0
       
EACH 7   SOLE DISPOSITIVE POWER:
REPORTING    
PERSON   3,186,298
       
WITH: 8   SHARED DISPOSITIVE POWER:
     
    0
     
9   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:
   
  3,186,298
     
10   CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):
   
  o
     
11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9):
   
  10.5%
     
12   TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):
   
  OO

Page 4 of 16 Pages

 

                     
CUSIP No.
  
59101M 10 5 
                

 

           
1   NAMES OF REPORTING PERSONS:
Harvey B. Cash (a Managing Director of InterWest Management Partners VII, LLC)
   
  I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY): 
   
     
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):
  (a)   o
  (b)   o
     
3   SEC USE ONLY:
   
   
     
4   CITIZENSHIP OR PLACE OF ORGANIZATION:
   
  United States
       
  5   SOLE VOTING POWER:
     
NUMBER OF   50,000
       
SHARES 6   SHARED VOTING POWER:
BENEFICIALLY    
OWNED BY   3,186,298
       
EACH 7   SOLE DISPOSITIVE POWER:
REPORTING    
PERSON   50,000
       
WITH: 8   SHARED DISPOSITIVE POWER:
     
    3,186,298
     
9   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:
   
  3,236,298
     
10   CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):
   
  o
     
11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9):
   
  10.7%
     
12   TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):
   
  IN
Neither the filing of this statement on Schedule 13G nor any of its contents shall be deemed to constitute an admission by Harvey B. Cash that he is the beneficial owner of any of the Common Stock referred to herein for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, or for any other purpose, and such beneficial ownership is expressly disclaimed, except to the extent of his pecuniary interest.

Page 5 of 16 Pages

 

                     
CUSIP No.
  
59101M 10 5 
                

 

           
1   NAMES OF REPORTING PERSONS:
Philip T. Gianos (a Managing Director of InterWest Management Partners VII, LLC)
   
  I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY): 
   
     
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):
  (a)   o
  (b)   o
     
3   SEC USE ONLY:
   
   
     
4   CITIZENSHIP OR PLACE OF ORGANIZATION:
   
  United States
       
  5   SOLE VOTING POWER:
     
NUMBER OF   0
       
SHARES 6   SHARED VOTING POWER:
BENEFICIALLY    
OWNED BY   3,186,298
       
EACH 7   SOLE DISPOSITIVE POWER:
REPORTING    
PERSON   0
       
WITH: 8   SHARED DISPOSITIVE POWER:
     
    3,186,298
     
9   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:
   
  3,186,298
     
10   CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):
   
  o
     
11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9):
   
  10.5%
     
12   TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):
   
  IN
Neither the filing of this statement on Schedule 13G nor any of its contents shall be deemed to constitute an admission by Philip T. Gianos that he is the beneficial owner of any of the Common Stock referred to herein for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, or for any other purpose, and such beneficial ownership is expressly disclaimed, except to the extent of his pecuniary interest.

Page 6 of 16 Pages

 

                     
CUSIP No.
  
59101M 10 5 
                

 

           
1   NAMES OF REPORTING PERSONS:
W. Scott Hedrick (a Managing Director of InterWest Management Partners VII, LLC)
   
  I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY): 
   
     
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):
  (a)   o
  (b)   o
     
3   SEC USE ONLY:
   
   
     
4   CITIZENSHIP OR PLACE OF ORGANIZATION:
   
  United States
       
  5   SOLE VOTING POWER:
     
NUMBER OF   0
       
SHARES 6   SHARED VOTING POWER:
BENEFICIALLY    
OWNED BY   3,186,298
       
EACH 7   SOLE DISPOSITIVE POWER:
REPORTING    
PERSON   0
       
WITH: 8   SHARED DISPOSITIVE POWER:
     
    3,186,298
     
9   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:
   
  3,186,298
     
10   CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):
   
  o
     
11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9):
   
  10.5%
     
12   TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):
   
  IN
Neither the filing of this statement on Schedule 13G nor any of its contents shall be deemed to constitute an admission by W. Scott Hedrick that he is the beneficial owner of any of the Common Stock referred to herein for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, or for any other purpose, and such beneficial ownership is expressly disclaimed, except to the extent of his pecuniary interest.

Page 7 of 16 Pages

 

                     
CUSIP No.
  
59101M 10 5 
                

 

           
1   NAMES OF REPORTING PERSONS:
W. Stephen Holmes III (a Managing Director of InterWest Management Partners VII, LLC)
   
  I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY): 
   
     
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):
  (a)   o
  (b)   o
     
3   SEC USE ONLY:
   
   
     
4   CITIZENSHIP OR PLACE OF ORGANIZATION:
   
  United States
       
  5   SOLE VOTING POWER:
     
NUMBER OF   0
       
SHARES 6   SHARED VOTING POWER:
BENEFICIALLY    
OWNED BY   3,186,298
       
EACH 7   SOLE DISPOSITIVE POWER:
REPORTING    
PERSON   0
       
WITH: 8   SHARED DISPOSITIVE POWER:
     
    3,186,298
     
9   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:
   
  3,186,298
     
10   CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):
   
  o
     
11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9):
   
  10.5%
     
12   TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):
   
  IN
Neither the filing of this statement on Schedule 13G nor any of its contents shall be deemed to constitute an admission by W. Stephen Holmes III that he is the beneficial owner of any of the Common Stock referred to herein for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, or for any other purpose, and such beneficial ownership is expressly disclaimed, except to the extent of his pecuniary interest.

Page 8 of 16 Pages

 

                     
CUSIP No.
  
59101M 10 5 
                

 

           
1   NAMES OF REPORTING PERSONS:
Gilbert H. Kliman (a Managing Director of InterWest Management Partners VII, LLC)
   
  I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY): 
   
     
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):
  (a)   o
  (b)   o
     
3   SEC USE ONLY:
   
   
     
4   CITIZENSHIP OR PLACE OF ORGANIZATION:
   
  United States
       
  5   SOLE VOTING POWER:
     
NUMBER OF   0
       
SHARES 6   SHARED VOTING POWER:
BENEFICIALLY    
OWNED BY   3,186,298
       
EACH 7   SOLE DISPOSITIVE POWER:
REPORTING    
PERSON   0
       
WITH: 8   SHARED DISPOSITIVE POWER:
     
    3,186,298
     
9   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:
   
  3,186,298
     
10   CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):
   
  o
     
11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9):
   
  10.5%
     
12   TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):
   
  IN
Neither the filing of this statement on Schedule 13G nor any of its contents shall be deemed to constitute an admission by Gilbert H. Kliman that he is the beneficial owner of any of the Common Stock referred to herein for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, or for any other purpose, and such beneficial ownership is expressly disclaimed, except to the extent of his pecuniary interest.

Page 9 of 16 Pages

 

                     
CUSIP No.
  
59101M 10 5 
                

 

           
1   NAMES OF REPORTING PERSONS:
Arnold L. Oronsky (a Managing Director of InterWest Management Partners VII, LLC)
   
  I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY): 
   
     
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):
  (a)   o
  (b)   o
     
3   SEC USE ONLY:
   
   
     
4   CITIZENSHIP OR PLACE OF ORGANIZATION:
   
  United States
       
  5   SOLE VOTING POWER:
     
NUMBER OF   37,499
       
SHARES 6   SHARED VOTING POWER:
BENEFICIALLY    
OWNED BY   3,186,298
       
EACH 7   SOLE DISPOSITIVE POWER:
REPORTING    
PERSON   37,499
       
WITH: 8   SHARED DISPOSITIVE POWER:
     
    3,186,298
     
9   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:
   
  3,223,797
     
10   CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):
   
  o
     
11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9):
   
  10.6%
     
12   TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):
   
  IN
Neither the filing of this statement on Schedule 13G nor any of its contents shall be deemed to constitute an admission by Arnold L. Oronsky that he is the beneficial owner of any of the Common Stock referred to herein for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, or for any other purpose, and such beneficial ownership is expressly disclaimed, except to the extent of his pecuniary interest.

Page 10 of 16 Pages

 

                     
CUSIP No.
  
59101M 10 5 
                

 

           
1   NAMES OF REPORTING PERSONS:
Thomas L. Rosch (a Managing Director of InterWest Management Partners VII, LLC)
   
  I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY): 
   
     
2   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS):
  (a)   o
  (b)   o
     
3   SEC USE ONLY:
   
   
     
4   CITIZENSHIP OR PLACE OF ORGANIZATION:
   
  United States
       
  5   SOLE VOTING POWER:
     
NUMBER OF   0
       
SHARES 6   SHARED VOTING POWER:
BENEFICIALLY    
OWNED BY   3,186,298
       
EACH 7   SOLE DISPOSITIVE POWER:
REPORTING    
PERSON   0
       
WITH: 8   SHARED DISPOSITIVE POWER:
     
    3,186,298
     
9   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON:
   
  3,186,298
     
10   CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES (SEE INSTRUCTIONS):
   
  o
     
11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9):
   
  10.5%
     
12   TYPE OF REPORTING PERSON (SEE INSTRUCTIONS):
   
  IN
Neither the filing of this statement on Schedule 13G nor any of its contents shall be deemed to constitute an admission by Thomas L. Rosch that he is the beneficial owner of any of the Common Stock referred to herein for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended, or for any other purpose, and such beneficial ownership is expressly disclaimed, except to the extent of his pecuniary interest.

Page 11 of 16 Pages

 

         
ITEM 1.
        
 
        
(a)   NAME OF ISSUER: Metabasis Therapeutics, Inc.
 
        
(b)   ADDRESS OF ISSUER’S PRINCIPAL EXECUTIVE OFFICE:
 
        
    11119 North Torrey Pines Road, La Jolla, CA 92037
 
        
ITEM 2.
        
 
        
(a)   NAME OF PERSON(S) FILING:
 
        
    InterWest Partners VII, LP (“IWP VII”)
    InterWest Investors VII, LP (“II VII”)
    InterWest Management Partners VII, LLC (“IMP VII”)
    Harvey B. Cash (“Cash”)
    Philip T. Gianos (“Gianos”)
    W. Scott Hedrick (“Hedrick”)
    W. Stephen Holmes III (“Holmes”)
    Gilbert H. Kliman (“Kliman”)
    Arnold L. Oronsky (“Oronsky”)
    Thomas L. Rosch (“Rosch”)
 
        
(b)   ADDRESS OF PRINCIPAL BUSINESS OFFICE OR, IF NONE, RESIDENCE:
 
        
    2710 Sand Hill Road, Second Floor, Menlo Park, CA 94025
 
        
(c)   CITIZENSHIP/PLACE OF ORGANIZATION:
 
        
 
  IWP VII:   California
 
  II VII:   California
 
  IMP VII:   California
 
  Cash:   United States
 
  Gianos:   United States
 
  Hedrick:   United States
 
  Holmes:   United States
 
  Kliman:   United States
 
  Oronsky:   United States
 
  Rosch:   United States

Page 12 of 16 Pages

 

         
(d)   TITLE OF CLASS OF SECURITIES: Common Stock
 
        
(e)   CUSIP NUMBER: 59101M 10 5
 
        
ITEM 3.   NOT APPLICABLE.
 
        
ITEM 4.   OWNERSHIP.
                         
    IWP VII (1)     II VII (2)     IMP VII (3)  
Beneficial Ownership
     3,040,686       145,612       3,186,298  
Percentage of Class
     10.0 %     0.5 %     10.5 %
Sole Voting Power
     3,040,686       145,612       3,186,298  
Shared Voting Power
     0       0       0  
Sole Dispositive Power
     3,040,686       145,612       3,186,298  
Shared Dispositive Power
     0       0       0  
                         
    Cash (4)     Gianos (4)     Hedrick (4)  
Beneficial Ownership
     3,236,298       3,186,298       3,186,298  
Percentage of Class
     10.7 %     10.5 %     10.5 %
Sole Voting Power
     50,000       0       0  
Shared Voting Power
     3,186,298       3,186,298       3,186,298  
Sole Dispositive Power
     50,000       0       0  
Shared Dispositive Power
     3,186,298       3,186,298       3,186,298  
                                 
    Holmes (4)     Kliman (4)     Oronsky (4)**     Rosch (4)  
Beneficial Ownership
     3,186,298       3,186,298       3,223,797       3,186,298  
Percentage of Class
     10.5 %     10.5 %     10.6 %     10.5 %
Sole Voting Power
     0       0       37,499       0  
Shared Voting Power
     3,186,298       3,186,298       3,186,298       3,186,298  
Sole Dispositive Power
     0       0       37,499       0  
Shared Dispositive Power
     3,186,298       3,186,298       3,186,298       3,186,298  
 
**   Includes 37,499 shares issuable to Oronsky pursuant to outstanding options exercisable within 60 days of December 31, 2006.
 
(1)   Includes 530,233 shares issuable pursuant to warrant exercise within 60 days of December 31, 2006.
 
(2)   Includes 25,392 shares issuable pursuant to warrant exercise within 60 days of December 31, 2006.
 
(3)   IMP VII is the general partner of IWP VII and II VII.
 
(4)   Cash, Gianos, Hedrick, Holmes, Kliman, Oronsky, and Rosch are Managing Directors of IMP VII.

Page 13 of 16 Pages

 

ITEM 5. OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS.
Not applicable.
ITEM 6. OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON.
Under certain circumstances set forth in the limited liability company operating agreement of IMP VII, the members of such limited liability company have the right to receive dividends from, or the proceeds from the sale of, the common stock of Issuer beneficially owned by such limited liability company.
ITEM 7. IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH ACQUIRED THE SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY.
Not applicable.
ITEM 8. IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP.
No reporting person is a member of a group as defined in section 240.13d-1(b)(1)(iii)(H) of the Act.
ITEM 9. NOTICE OF DISSOLUTION OF THE GROUP.
Not applicable.
ITEM 10. CERTIFICATION.
Not applicable.
EXHIBITS
Joint Filing Statement attached as Exhibit A.

Page 14 of 16 Pages

 

SIGNATURE
After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.
Date: February 14, 2007
                 
        INTERWEST PARTNERS VII, LP
 
                
        By:   InterWest Management Partners VII, LLC
its General Partner
By:
  /s/ Harvey B. Cash            
 
               
Name:
  Harvey B. Cash            
 
                
By:
  /s/ Philip T. Gianos       By:   /s/ W. Stephen Holmes
 
               
Name:
  Philip T. Gianos           Managing Director
 
                
        INTERWEST INVESTORS VII, LP
 
                
By:
  /s/ W. Scott Hedrick            
 
               
Name:   W. Scott Hedrick   By:   InterWest Management Partners VII, LLC
its General Partner
 
                
By:
  /s/ W. Stephen Holmes       By:   /s/ W. Stephen Holmes
 
               
Name:
  W. Stephen Holmes           Managing Director
 
                
By:
  /s/ Gilbert H. Kliman            
 
               
Name:
  Gilbert H. Kliman            
 
                
        INTERWEST MANAGEMENT PARTNERS VII, LLC
 
                
By:   /s/ Arnold L. Oronsky   By:   /s/ W. Stephen Holmes
             
Name:   Arnold L. Oronsky       Managing Director
 
                
By:
  /s/ Thomas L. Rosch            
 
               
Name:
  Thomas L. Rosch            

Page 15 of 16 Pages

 

EXHIBIT A
Joint Filing Statement
We, the undersigned, hereby express our agreement that the attached Schedule 13G is filed on behalf of each of us.
                 
Date: February 14, 2007   INTERWEST PARTNERS VII, LP
 
                
        By:   InterWest Management Partners VII, LLC
its General Partner
By:
  /s/ Harvey B. Cash            
 
               
Name:
  Harvey B. Cash            
 
                
By:
  /s/ Philip T. Gianos       By:   /s/ W. Stephen Holmes
 
               
Name:
  Philip T. Gianos           Managing Director
 
                
        INTERWEST INVESTORS VII, LP
 
                
By:
  /s/ W. Scott Hedrick            
 
               
Name:   W. Scott Hedrick   By:   InterWest Management Partners VII, LLC
its General Partner
 
                
By:
  /s/ W. Stephen Holmes       By:   /s/ W. Stephen Holmes
 
               
Name:
  W. Stephen Holmes           Managing Director
 
                
By:
  /s/ Gilbert H. Kliman            
 
               
Name:
  Gilbert H. Kliman            
 
                
        INTERWEST MANAGEMENT PARTNERS VII, LLC
 
                
By:   /s/ Arnold L. Oronsky   By:   /s/ W. Stephen Holmes
             
Name:   Arnold L. Oronsky       Managing Director
 
                
By:
  /s/ Thomas L. Rosch            
 
               
Name:
  Thomas L. Rosch            

Page 16 of 16 Pages