The invention discloses 424 novel phosphorylation sites identified in signal transduction proteins and pathways underlying human Leukemia, 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, Cytoskeletal proteins, Cellular Metabolism enzymes, G Protein/GTPase Activating/Guanine Nucleotide Exchange Factor proteins, Immunoglobulin Superfamily proteins, Inhibitor proteins, Lipid Kinases, Nuclear DNA Repair/RNA Binding/Transcription proteins, Serine/Threonine Protein Kinases, Tyrosine Kinases, Protein Phosphatases, and Translation/Transporter proteins.