An inhibitor of VEGFRs (IC50s = 0.38, 0.02, 0.18, and 0.23 μM for human VEGFR1, 2, 3, and mouse Vegfr2, respectively); selective for VEGFRs over FGFRs and PDGFRα (IC50s = >10 μM), but has activity at PDGFRβ (IC50 = 1.4 μM) in an enzyme assay; inhibits VEGF-induced VEGFR2 autophosphorylation (IC50 = 11.5 nM in CHO cells transfected with the human receptor); blocks bFGF- and VEGF-induced angiogenesis (ED50s = 9 and 26 mg/kg, respectively) in a mouse model of growth factor-induced angiogenesis