TKI258 inhibits proliferation and survival of KG1 and KG1A and induces apoptosis. TKI258 treatment results in (A) reduced viability and (B) increased cell death (where the curves fall below 100% of day-0 reading) in KG1 and KG1A cell lines assessed at 48 hours, in contrast to the nonresponsive HEL cell line. Values are means plus or minus SE of 3 independent experiments. (C) TKI258 treatment resulted in a dose-dependent increase in apoptosis, assessed by a colorimetric caspase assay, in KG1 and KG1A compared with HEL. Values are means plus or minus SD of 3 separate experiments and are normalized to 1.0 at 0 nM TKI258. (D) Increased apoptosis in KG1 cells was confirmed by the TUNEL assay. Values are means plus or minus SD of 2 separate experiments. (E) Reduced phosphorylation of the FGFR1OP2-FGFR1 fusion protein and STAT5 after TKI258 treatment.