FGFR inhibition sensitizes TPC1 cells to RET inhibitors. (A) Short-term proliferation assay (48 h) of TPC1 cells treated with 100 nM BLU6864 alone or in combination with indicated doses of BGJ398; representative dose–response curves are shown from three independent experiments. (B) EC₅₀ values of the indicated drug combinations as determined from A. (C) Long-term proliferation assay of TPC1 cells treated with XL184 or BLU6864 alone or in combination with BGJ398. Cells were treated for 7 d at 250 nM and stained with crystal violet. Three independent experiments were performed, and a representative plate is displayed. (D) Quantification of long-term viability of TPC1 cells treated with the indicated compounds was performed by calculating colony intensity; the mean and SD are displayed for technical replicates from one of three biological replicates. *, P < 0.05; **, P < 0.01; ***, P < 0.001, Student’s t test.