Erdafitinib (JNJ-42756493) inhibits the tyrosine kinase activities of FGFR1-4 in time-resolved fluorescence assays with IC50 values of 1.2, 2.5, 3.0 and 5.7 nM, respectively. The closely related VEGFR2 kinase is less potently inhibited (30-fold less potent compared to FGFR1) by erdafitinib, with an IC50 value of 36.8 nM. Erdafitinib binds FGFR1, 3, 4, and 2 with Kd values of 0.24, 1.1, 1.4 and 2.2 nM, respectively. The Kd value for VEGFR2 is higher at 6.6 nM. Erdafitinib inhibits proliferation of FGFR1, 3, and 4 expressing cells with IC50 values of 22.1, 13.2, and 25nM, respectively.