FES is required for KIT^D816V-induced cell proliferation. Following siRNA treatment, cells were seeded in 96-well plates and maintained with or without cytokine as indicated. Thymidine incorporation assays were done 24 hours later. Cells were TF-1 KIT^D816V (A,B), TF-1 (C), and P815 (D). Cell proliferation is represented as a percentage of control siRNA. The data are from 3 independent experiments done in triplicate. Error bars indicate the standard error of the mean.