A multi-kinase inhibitor; inhibits growth and induces apoptosis in Ba/F3 and AML cell lines expressing constitutively active FLT3 (IC50s = 150-650 nM) but not those expressing TEL-ABL, TEL-JAK2, or BCR-ABL (IC50s = >10 μM); inhibits C-KIT, VEGFR, and PDGFRβ in vitro (IC50s = 0.03, 0.46, and 0.36 μM, respectively)