Linifanib (AL-39324) (ABT-869) is a novel, potent ATP-competitive VEGFR/PDGFR inhibitor for KDR (IC50: 4 nM), CSF-1R (IC50: 3 nM), Flt-1/3 (IC50: 3/4 nM) and PDGFRβ (IC50: 66 nM). Linifanib may exhibit potent antiproliferative and apoptotic effects on tumor cells whose proliferation is dependent on mutant kinases, such as FMS-related tyrosine kinase receptor-3 (FLT3).