Hematopoietic colonies from EMS patients show a greater, dose-dependent response to TKI258 than normal peripheral blood cells. (A) Overall and median responses in methylcellulose colony assays of 10 normal peripheral blood samples and EMS cases 1, 2, 3, and 5 (P = .02). (B) Dose response in colony reduction (± SD). A greater differential response was seen at 100 nM than 20 nM compared with healthy controls (P = .01 and P = .08, respectively).