1 TITLE: Peptide immunoaffinity enrichment and targeted mass spectrometry enables multiplex, quantitative pharmacodynamic studies of phospho-signaling AUTHORS: Jeffrey R. Whiteaker, Lei Zhao, Ping Yan, Richard G. Ivey, Uliana J. Voytovich, Heather D. Moore, Chenwei Lin, Amanda G. Paulovich AFFILIATION: Fred Hutchinson Cancer Research Center 1100 Fairview Ave. N. Seattle, WA 98109 CONTACT INFORMATION: Amanda G. Paulovich Fred Hutchinson Cancer Research Center 1100 Fairview Ave. N. Seattle, WA 98109 Phone 206-667-1912, Fax 206-667-2277 email: apaulovi@fredhutch.org RUNNING TITLE: Peptide immuno-MRM enables phosphopeptide quantification ABBREVIATIONS: pharmacodynamic (PD), multiple reaction monitoring (MRM), post- translational modifications (PTMs), mass spectrometry (MS), DNA damage response (DDR), methyl methanesulfonate (MMS), ionizing radiation (IR), lymphoblast cell line (LCL), Western blot (WB) MCP Papers in Press. Published on May 18, 2015 as Manuscript O115.050351 Copyright 2015 by The American Society for Biochemistry and Molecular Biology, Inc.