Potent inhibitor of EGFR, ErbB2 and Abl receptor tyrosine kinases (IC50 values are 0.5-2, 19 and 41 nM, respectively). Also weak inhibitor of FLT1 and Src. Inhibits EGFR and ErbB2 autophosphorylation in vitro in NSCLC and T-47D breast cancer cell lines, respectively. Inhibits tumor growth of EGFR-overexpressing A431 and ErbB2 overexpressing BT-474 tumor xenografts in mice. Purity 98%. MW (observed): 507