Inhibition of VEGFR2 (KDR) and FGFR3 phosphorylation by BIBF 1000. (A) Cultured marrow stroma cells were exposed to VEGF (50 ng/mL) in the presence of increasing concentrations of BIBF 1000 for 5 minutes. Dose-dependent abrogation of VEGFR2 phosphorylation (top: anti–p-Tyr100 immunoblots, densitometry) and corresponding immunoblots of total VEGFR2 (bottom) are shown. (B) OPM-2 cells known to express a constitutively active FGFR3 mutant were incubated with increasing concentrations of BIBF 1000 for 5 minutes. FGFR3 phosphorylation was inhibited in a dose-dependent manner (top: anti–p-Tyr85 immunoblots, densitometry). Bottom panel shows corresponding immunoblots of total FGFR3.