AEE788 is a multitargeted human epidermal receptor (HER) 1/2 and vascular endothelial growth factor receptor (VEGFR) 1/2 receptor family tyrosine kinases inhibitor with IC<sub>50</sub> of 2, 6, 77, 59 nM for EGFR, ErbB2, KDR, and Flt-1. In cells, growth factor-induced EGFR and ErbB2 phosphorylation was also efficiently inhibited with IC<sub>50</sub>s of 11 and 220 nM, respectively. It efficiently inhibited growth factor-induced EGFR and ErbB2 phosphorylation in tumors for >72 h, a phenomenon correlating with the antitumor efficacy of intermittent treatment schedules. It also inhibits VEGF-induced angiogenesis in a murine implant model. It has potential as an anticancer agent targeting deregulated tumor cell proliferation as well as angiogenic parameters.