EXHIBIT A
AGREEMENT JOINT FILING OF SCHEDULE 13D

Pursuant to Rule 13d-1(k)(l) promulgated pursuant to the Securities Exchange Act of 1934, as amended, the undersigned agree that the attached Schedule 13D is being filed on behalf of each of the undersigned.

April 20, 2011		GRANITE GLOBAL VENTURES (Q.P.) L.P. GRANITE GLOBAL VENTURES L.P.
		BY:		GRANITE GLOBAL VENTURES L.L.C.
		ITS:		GENERAL PARTNER
		By:		/s/ Hany M. Nada
				Hany M. Nada Manager
April 20, 2011		GRANITE GLOBAL VENTURES III L.P. GGV III ENTREPRENEURS FUND L.P.
		BY:		GRANITE GLOBAL VENTURES III L.L.C.
		ITS:		GENERAL PARTNER
		By:		/s/ Hany M. Nada
				Hany M. Nada Manager
April 20, 2011		GRANITE GLOBAL VENTURES L.L.C.
		By:		/s/ Hany M. Nada
				Hany M. Nada Manager
April 20, 2011		GRANITE GLOBAL VENTURES III L.L.C.
		By:		/s/ Hany M. Nada
				Hany M. Nada Manager
April 20, 2011		By:		/s/ Hany M. Nada
				Hany M. Nada as Attorney-in-fact for Ray A. Rothrock
April 20, 2011		By:		/s/ Hany M. Nada
				Hany M. Nada as Attorney-in-fact for Anthony Sun
April 20, 2011		By:		/s/ Hany M. Nada
				Hany M. Nada as Attorney-in-fact for Scott B. Bonham
April 20, 2011		By:		/s/ Hany M. Nada
				Hany M. Nada as Attorney-in-fact for Joel D. Kellman
April 20, 2011		By:		/s/ Hany M. Nada
				Hany M. Nada
April 20, 2011		By:		/s/ Hany M. Nada
				Hany M. Nada as Attorney-in-fact for Thomas K. Ng
April 20, 2011		By:		/s/ Hany M. Nada
				Hany M. Nada as Attorney-in-fact for Jixun Foo
April 20, 2011		By:		/s/ Hany M. Nada
				Hany M. Nada as Attorney-in-fact for Glenn Solomon
April 20, 2011		By:		/s/ Hany M. Nada
				Hany M. Nada as Attorney-in-fact for Jenny Lee
April 20, 2011		By:		/s/ Hany M. Nada
				Hany M. Nada as Attorney-in-fact for Jessie Jin
April 20, 2011		By:		/s/ Hany M. Nada
				Hany M. Nada as Attorney-in-fact for Fumin Zhuo