Security	Date	Code	Shares	Price	A/D	Owned after	D/I	Nature of ownership
Common Stock^F2,F3	Jul 7, 2015	S	25,737	$27.5452	D	299,749	I	MDV IX, L.P., as nominee for MDV IX, L.P., and MDV ENF IX, L.P.
Common Stock^F4,F3	Jul 8, 2015	S	3,100	$27.551	D	296,649	I	MDV IX, L.P., as nominee for MDV IX, L.P., and MDV ENF IX, L.P.
Common Stock^F5	holding	—	—		—	3,772,686	I	MDV VII LP, nom for MDV VII LP, MDV VII Leaders' Fund LP, MDV ENF VII (A) LP, and MDV ENF VII (B) LP
Common Stock^F5	holding	—	—		—	265,150	I	MDV VII, L.P.
Common Stock^F5	holding	—	—		—	6,043	I	MDV ENF VII (A), L.P.
Common Stock^F5	holding	—	—		—	3,146	I	MDV ENF VII (B), L.P.
Common Stock^F5	holding	—	—		—	25,661	I	MDV VII Leaders' Fund, L.P.

Table II — derivative securities

No Table II lines on this filing.

Explanation of responses

F1The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by MDV IX on December 15, 2014.
F2Price reflected is the weighted-average sale price for shares sold. The range of the sale prices for the transaction was $27.50 and $27.84 per share. The Reporting Person undertakes to provide, upon request by the SEC staff, the Issuer, or security holder of the Issuer, full information regarding the number of shares sold at each separate price.
F3Ninth MDV Partners, L.L.C. is the general partner of MDV IX, L.P., as nominee for MDV IX, L.P. and MDV ENF IX, L.P. (collectively, "MDV IX"). William Ericson ("Ericson") and Jonathan Feiber ("Feiber") are Managing Members of Ninth MDV Partners, L.L.C. Ericson and Feiber may be deemed to share voting and dispositive power over the shares held by MDV IX. Each Reporting Person disclaims beneficial ownership of the shares held by MDV IX except to the extent of any pecuniary interest therein. Ericson is a director of the Issuer and, accordingly, files separate Section 16 reports.
F4Price reflected is the weighted-average sale price for shares sold. The range of the sale prices for the transaction was $27.50 and $27.72 per share. The Reporting Person undertakes to provide, upon request by the SEC staff, the Issuer, or security holder of the Issuer, full information regarding the number of shares sold at each separate price.
F5Seventh MDV Partners, L.L.C. is the general partner of (i) MDV VII, L.P., as nominee for MDV VII, L.P., MDV ENF VII(A), L.P., MDV ENF VII(B), L.P., and MDV VII Leaders' Fund, L.P., (ii) MDV VII, L.P., (iii) MDV ENF VII(A), L.P., (iv) MDV ENF VII(B), L.P., and (v) MDV VII Leaders' Fund, L.P. (collectively, "MDV VII"). Feiber and Nancy Schoendorf ("Schoendorf") are Managing Members of Seventh MDV Partners, L.L.C. Feiber and Schoendorf may be deemed to share voting and dispositive power over the shares held by MDV VII. Each Reporting Person disclaims beneficial ownership of the shares held by MDV VII except to the extent of any pecuniary interest therein. Ericson, a general partner with Mohr Davidow Ventures, may be deemed to indirectly beneficially own the shares affiliated with MDV VII. Ericson is a director of the Issuer and, accordingly, files separate Section 16 reports.