1-[3-[1-([1,1'-Biphenyl]-3-ylMethyl)-1H-1,2,3-triazol-5-yl]phenyl]-3-(4-chlorophenyl)-1H-pyrazolo[3,4-d]pyriMidin-4-aMine

Ki: 44 nM (c-Src)
Kd: 86 nM (c-Src)

KB SRC 4 (Compound 4) is a potent, highly selective c-Src inhibitor, with a K _i of 44 nM and a K _d of 86 nM, and shows no inhibition on c-Abl up to 125 μM. KB SRC 4 is selective between Src family members, with >2-fold selectivity over both Lck (K _d , 160 nM) and Fgr (K _d , 240 nM), 8-fold selectivity over c-Yes (K _d , 720 nM), and >40-fold selectivity over Lyn (K _d , 3200 nM), Hck (K _d , 4400 nM), and Fyn (K _d , >40000 nM). KB SRC 4 inhibits the growth of cancer cell lines, with GI ₅₀ s of 11 μM, 12 μM, 11 μM, 6.0 μM against HT-29, SK-BR-3, MCF7, MDA-MB-453, and NIH-3T3, respectively.