The invention discloses nearly 123 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: protein kinases, adaptor/scaffold proteins, phosphatase/phospholipases, G proteins/GTPase activating proteins/guanine nucleotide exchange factors, cellular metabolism enzymes, DNA binding proteins, cytoskeletal proteins, cell cycle regulation proteins, proteases, RNA binding proteins, transcription proteins, translation initiation complex proteins, transferases, ubiquitin conjugating system proteins, vesicle proteins, actin binding proteins, apoptosis proteins, chemokine proteins, enzyme proteins extra cellular matrix proteins, helicases, hydrolases, immunoglobin superfamily proteins, inhibitor proteins, isomerases, ligases, lipid binding proteins, methyltransferases, motor proteins, receptor proteins, and chaperone proteins.