POWER OF ATTORNEY

     Know all by these presents,that the undersigned
hereby constitutes and appoints each of Sujal Shah, Charles
McWherter, Matthew Hemington, and Brett White, signing
individually, the undersigned's true and lawful attorneys-in-
fact and agents to:
     (1)  execute for and on behalf of the undersigned,an
officer, director,or holder of 10% or more of a registered
class of securities of CymaBay Therapeutics, Inc.
(the "Company"),Forms 3, 4 and 5 in accordance with
Section 16 (a) of the Securities Exchange Act of 1934,
as amended (the "Exchange Act") and the rules thereunder;
     (2)  do and perform any and all acts for an on behalf
of the undersigned that may be necessary or desirable to
complete and execute such Form 3, 4 or 5, complete and
execute any amendment or amendments thereto, and timely
file such forms or amendments with the United States
Securities and Exchange Commission and any stock exchange
or similar authority; and
     (3)  take any other action of any nature whatsoever
in connection with the foregoing which, in the opinion
of such attorney-in-fact, may be of benefit, in the best
interest of, or legally required by, the undersigned,
it being understood that the documents executed by such
attorney-in-fact on behalf of the undersigned pursuant to
this Power of Attorney shall be in such form and shall
contain such terms and conditions as such attorney-in-fact
may approve in such attorney-in-fact's discretion.
     The undersigned hereby grants to each such attorney-
in-fact full power and authority to do and perform any
and every act and thing whatsoever requisite, necessary
or proper to be done in the exercise of any rights and
powers herein granted, as fully to all intents and
purposes as the undersigned might or could do if
personally present, with full power of substitution
or revocation, hereby ratifying and confirming all that
such attorney-in-fact, or such attorney-in-fact's
substitute or substitutes, shall lawfully do or cause
to be done by virtue of this power of attorney and the
rights and powers herein granted.  The undersigned
acknowledges that the foregoing attorneys-in-fact, in
serving in such capacity at the request of the
undersigned, are not assuming, nor is the Company assuming,
any of the undersigned's responsibilities to comply with
Section 16 of the Exchange Act.
     This Power of Attorney shall remain in full force
and effect until the earliest to occur of (a) the
undersigned is no longer required to file Forms 3, 4
and 5 with respect to the undersigned's holdings of
and transactions in securities issued by the Company,
(b) revocation by the undersigned in a signed writing
delivered to the foregoing attorneys-in fact or (c) as
to any attorney-in-fact individually, until such
attorney-in-fact shall no longer be employed by the
Company or Cooley LLP.as the case may be.
IN WITNESS WHEREOF, the undersigned has caused this
Power of Attorney to be executed as of this 27th day
of April, 2015.

/s/ Kirk Rosemark
    Kirk Rosemark