Selective inhibitor of Src-family tyrosine kinases. Inhibits p56lck and p59fynT (IC50 values are 4 and 5 nM respectively). Displays > 10000-fold selectivity over ZAP-70 and JAK2. Moderately inhibits CSK (IC50 = 0.73 μM). Negative control PP 3 (Cat. No. 2794) also available.