In this study, we have used both FGFR1-dependent murine leukemia cell lines carrying different chimeric FGFR1 fusion kinases as well as FGFR1-dependent lung and breast cancer lines with amplification of FGFR1, to compare the ability of 5 different pan-FGFR inhibitors to suppress FGFR1 activation and subsequent leukemogenesis, We show that BGJ398 is the most efficient inhibitor based on in vitro cell growth inhibition and apoptosis assays. The gene discussed is FGFR1; the disease is breast cancer.