SU1498 is a potent and selective inhibitor of the VEGFR2 receptor kinase, Flk-1 with an IC50 value of 700 nM. SU1498 is a very weak inhibitor of PDGFR-kinase, EGFR-kinase and HER-2 kinase with IC50 values > 50 µM. SU1498 has been used to study the role of VEGFR2 (Flk-1) in a variety of biological activities including angiogenesis, tumor growth inhibition, and stem cell proliferation.