The Src family of non-receptor tyrosine kinases regulate cell adhesion, growth, and differentiation through activation of multiple intracellular signaling pathways. Normally inactive, Src kinases are transiently activated during mitosis and constitutively activated by abnormal mutations. PP2 is a potent, reversible, ATP-competitive, and selective inhibitor of the Src family of protein tyrosine kinases. It inhibits p56lck (IC50 = 4 nM), p59fynT (IC50 = 5 nM), Hck (IC50 = 5 nM), and Src (IC50 = 100 nM). PP2 does not significantly affect the activity of EGFR kinase (IC50 = 480 nM), JAK2 (IC50 > 50 μM), or ZAP-70 (IC50 > 100 μM). PP2 inhibits the activation of focal adhesion kinase as well as its phosphorylation at Tyr577. PP2 also inhibits anti-CD3-stimulated tyrosine phosphorylation of human T-cells with an IC50 value of 600 nM.
