A suppressor of EGFR and ErbB2 (IC50s = 0.5 and 14 nM, respectively); enhances the cytotoxicity of adriamycin in a concentration-dependent manner in multidrug-resistant A549T lung cancer cells with overexpressed P-glycoprotein; curbs tumor growth in ErbB2-amplified NCI-N87 and NUGC4 gastric cancer mouse xenograft models at 20 mg/kg