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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(Print or Type Responses)

1. Name and Address of Reporting Person * Foresite Capital Management I, LLC   2. Issuer Name and Ticker or Trading Symbol AMBIT BIOSCIENCES CORP [AMBI] 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) 3052 PACIFIC AVENUE 3. Date of Earliest Transaction (Month/Day/Year) 05/17/2013 (Street) SAN FRANCISCO, CA 94115 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 05/17/2013   P   36,616 A $ 6.7717 2,036,616 I See footnote (1) Common Stock 05/20/2013   P   8,120 A $ 6.9025 2,044,736 I See footnote (1) Common Stock 05/21/2013   P   1,811 A $ 6.8362 2,046,547 I See footnote (1) Common Stock 05/22/2013   P   5,005 A $ 6.7391 2,051,552 I See footnote (1) Common Stock 06/03/2013   P   10,000 A $ 6.9908 2,061,552 I See footnote (1) Common Stock 06/12/2013   P   5,700 A $ 7.4532 2,067,252 I See footnote (1) Common Stock 06/14/2013   P   7,500 A $ 7.4616 2,074,752 I See footnote (1) Common Stock 06/24/2013   P   4,817 A $ 6.7664 2,079,569 I See footnote (1)

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
Foresite Capital Management I, LLC 3052 PACIFIC AVENUE SAN FRANCISCO, CA 94115		X
Foresite Capital Fund I, L.P. 3052 PACIFIC AVENUE SAN FRANCISCO, CA 94115		X
Tananbaum James B. 3052 PACIFIC AVENUE SAN FRANCISCO, CA 94115		X

Signatures

/s/ James B. Tananbaum, as managing member of Foresite Capital Management I, LLC		10/16/2013
**Signature of Reporting Person		Date
/s/ James B. Tananbaum, as managing member of the GP of Foresite Capital Fund I, L.P.		10/16/2013
**Signature of Reporting Person		Date
/s/ James B. Tananbaum		10/16/2013
**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)	Shares are owned directly by Foresite Capital Fund I, L.P. ("FCF I"). Foresite Capital Management I, LLC ("FCM I"), the Designated Filer and general partner of FCF I, may be deemed to have the sole voting and dispositive power over 2,074,752 shares of the Issuer's Common Stock. James Tananbaum ("Tananbaum"), in his capacity as managing member of FCM I, may be deemed to have the sole voting and dispositive power over 2,074,752 shares of the Issuer's Common Stock.
Remarks: Each Reporting Person disclaims the existence of a "group". Each of FCM I and its partners and Tananbaum disclaims beneficial ownership of any of these shares except to the extent of any pecuniary interest therein, and the filing of this report is not an admission that FCM I and its partners or Tananbaum is the beneficial owner of these shares for purposes of Section 16 or any other purpose.

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