Src and Src-family protein-tyrosine kinases are regulatory proteins that play key roles in cell differentiation, motility, proliferation, and survival. The initially described phosphorylation sites of Src include an activating phosphotyrosine 418 that results from autophosphorylation, and an inhibiting phosphotyrosine 529 that results from phosphorylation by C-terminal Src kinase (Csk) and Csk homologous kinase. Dephosphorylation of phosphotyrosine 529 increases Src kinase activity. This antibody panel can be used for determine the activity of Src by different specific phosphorylation site.