Potent and selective platelet-derived growth factor receptor β (PDGFRβ) inhibitor (IC50 = 10 nM) that displays > 14-fold, > 229-fold and > 10000-fold selectivity over VEGFR2, FGFR1 and EGFR respectively. Inhibits proliferation of HUVEC and NIH3T3 cells in vitro (IC50 = 0.11 μM).