Inhibition of FGFR fusion kinase activity repressed tumor growth in a mouse xenograft model. Inhibition of FGFR fusion kinase activity repressed tumor growth in a mouse xenograft model. A, inhibition of cell proliferation by the FGFR inhibitor PD173074. The FGFR3–BAIAP2L1 bladder cell line SW780, and 2 control bladder cell lines J82 (K652E mutation) and HT-1197 (S249C mutation), were tested for the effects of PD173074 at 3 concentrations on cell proliferation, assessed by the WST-1 method at the indicated times. Data shown are the means of triplicates. B, differential sensitivity of FGFR fusion-positive versus FGFR-mutant bladder cancer xenograft growth to PD173074. Mice xenografted with bladder cancer SW780 cells (FGFR3–BAIAP2L1 fusion), RT4 (FGFR3–TACC3 fusion), or J82 cells (K652E mutation) were treated daily with PD173074 after tumors were formed. The tumor size was monitored over a time course of 3 weeks. *, P < 0.05; **, P < 0.005.C, inhibition of the FGFR signaling pathway by the FGFR inhibitor PD173074 in mouse xenograft tumors. Bladder cancer SW780 cells were implanted in mice and treated with PD173074 after tumor formation as shown in B. Protein lysates of tumor tissues were prepared and immunoblotted with antibodies against phospho-ERK1/2, pan-ERK1/2, and γ-tubulin. Yi-Mi Wu et al. Cancer Discovery 2013;3:636-647 ©2013 by American Association for Cancer Research