The invention discloses 102 novel phosphorylation sites identified in signal transduction proteins and pathways downstream of c-Src kinase, and provides phosphorylation-site specific antibodies and heavy-isotope labeled peptides (AQUA peptides) for the selective detection and quantification of these phosphorylated sites/proteins, as well as methods of using the reagents for such purpose. Among the phosphorylation sites identified are sites occurring in the following protein types: Adaptor/Scaffold proteins, Actin Binding proteins, Cytoskeletal proteins, G protein/GTPase Activating protein/Guanine Nucleotide Exchange Factor proteins, Helicases, RNA Binding proteins, Transcription/Translation Factor or Initiation Complex proteins, Cellular Metabolism Enzymes, and Vesicle proteins.