Effect of three tyrosine kinase inhibitors on the proliferation of the 2 ROSA cell lines. Cells were cultured for 48 hours in the presence of imatinib, dasatinib or midostaurin (1 μM, provided in dimethylsulfoxide (DMSO) 0.1% final concentration) or in the presence of DMSO alone (0.1% final concentration) in the established culture medium (containing rhSCF at 80 ng/mL for ROSA^{KIT WT} cells but not for ROSA^{KIT D816V} cells). At the end of this incubation, 10 μL of MTT was added in each well and the cells were incubated for 3 additional hours at 37°C. The number of living cells was then measured for each condition by reading the absorbance at 570 nm, and the results were expressed as a percentage of living cells compared with the control (DMSO 0.1% alone). Data presented are the mean ± SD from 3 independent experiments. ***Significantly different from control (DMSO alone) at P < .0001.