-- Andrej Sali, Ph.D. Professor, Department of Bioengineering and Therapeutic Sciences Department of Pharmaceutical Chemistry California Institute for Quantitative Biosciences University of California, San Francisco UCSF MC 2552 Byers Hall Room 503B 1700 4th Street San Francisco, CA 94158-2330, USA Tel +1 (415) 514-4227; Fax +1 (415) 514-4231 Assistant: Ms. Hilary Mahon, hilary@salilab.org, Tel +1 (415)514-4228; Lab +1 (415) 514-4233, 4258 Email sali@salilab.org; Web http://salilab.org Begin forwarded message:

From: Dan Hostetter <dan@cytomx.com> Subject: Bioinformatics Summer Intern Posting_Ltr(2).docx Date: April 22, 2013 4:29:09 PM PDT To: Dave Barkan <davebarkan@gmail.com>, "sali@salilab.org" <sali@salilab.org> Cc: Luc Desnoyers <luc@cytomx.com>

Hi Dave and Andrej,

Hope you are both doing really well!

I’ve been having a great time applying my protease knowledge at CytomX . We have started our very first summer internship program and need bioinformatics expertise. I thought both of you would be a great resource for recommendations.

CytomX has applied the pro-drug concept to antibody therapeutics to address toxicities that occur when antibodies bind to target in healthy tissue. We call our protease activated antibodies “Probodies”. Our technology leverages protease activity that is present in tumor tissue and not healthy tissue to activate our Probodies. We would love to mine RNA expression databases for targets that fit certain criteria such as (1) extracellular and therefore accessible to an antibody therapeutic and (2) a protease that can cleave our Probody is also expressed. The ideal candidate would be comfortable working with RNA expression databases and able to create filters based on the needs of our Probody platform. I’ve attached a description of the intern position to this email as a Word document.

I’m copying Luc Desnoyers on this email. Luc is the head of our cell biology group and is a great mentor. The student intern would be working with Luc and someone in the cell biology group. I can vouch that everyone in Luc’s group is nice and all of them are patient teachers.

If you have anyone in mind that would be a good fit, please let us know. I’m confident they would have a great experience at CytomX.

Thanks guys!

Best, Dan