The invention discloses nearly 480 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, acetyltransferases, actin binding proteins, adhesion proteins, apoptosis proteins, calcium-binding proteins, cell cycle regulation proteins, cell surface proteins, channel proteins, chaperone proteins, contractile proteins, cytokine proteins, cytoskeletal proteins, G protein regulators and GTPase activating proteins, guanine nucleotide exchange factors, helicase proteins, immunoglobulin superfamily proteins, inhibitor proteins, protein kinases, lipid kinases, ligases, lipid binding proteins, methytransferases, motor proteins, oxidoreductases, phosphotases, phosphodiesterases, phospholipases, proteases, receptor proteins, trascription factors, transferases, translation/transporter proteins, and ubiquitin conjugating system proteins.