Genistein(NPI 031L), a phytoestrogen found in soy products, is a highly specific inhibitor of protein tyrosine kinase (PTK) which blocks the mitogenic effect mediated by EGF on NIH-3T3 cells with IC50 of 12μM or by insulin with IC50 of 19 μM.

A potent, selective, orally active EGFR inhibitor with IC50 of 23 nM.

PD 089828 is a competitive inhibitor of the receptor tyrosine kinases FGFR1, PDGFRβ, and EGFR (IC50s = 0.15, 1.76, and 5.47 μM, respectively) and a noncompetitive inhibitor of the nonreceptor tyrosine kinase c-Src (IC50 = 0.18 μM)