SUBSTITUTE POWER OF ATTORNEY

Pursuant to a written limited power of attorney,
a copy of which was previously filed
(the ?Power of Attorney?), the undersigned,
Scott Siamas, has been constituted and appointed
true and lawful attorney-in-fact and agent,
with full power of substitution and
resubstitution, to do and perform every act
and thing whatsoever requisite, necessary,
or proper to be done in the exercise of the
rights and powers granted in said
Power of Attorney, by the following individual:

Susan Wojcicki

Know all by these presents, that, pursuant to
the powers granted to the undersigned in the
Power of Attorney, the undersigned hereby
constitutes and appoints Lisa Yun as a
substitute to the undersigned attorney-in-fact,
with full power of substitution or
resubstitution, and with full power and
authority to do and perform every act and
thing whatsoever requisite, necessary, or
proper to be done in the exercise of the
rights and powers granted to the undersigned
in said Power of Attorney.  For the
avoidance of doubt, the foregoing appointment
shall not serve as a revocation of the powers
granted to the undersigned himself in the
Power of Attorney.

This Substitute Power of Attorney shall remain
in full force and effect unless and until
revoked by the undersigned.

IN WITNESS WHEREOF, the undersigned has caused
this Substitute Power of Attorney to be
executed as of this 22nd day of May, 2018.


Signature: /s/ Scott Siamas
Name:  Scott Siamas