Flt3 mutations, but not expression level, in primary AML blasts indicate sensitivity to VX-680. (A) Expression of Aur-A and Flt3 in the representative AML samples. Primary leukemic blasts obtained from AML patients were lysed, and proteins were analyzed by Western blot analysis with antibodies as indicated. GAPDH served as a loading control. (B) Expression of Flt3 does not predict apoptotic response to VX-680 (P > .05). Dot plot of apoptotic response in individual AML samples to VX-680 (50 nM) was grouped by level of Flt3 expression. (C,D) AML cases were further stratified by Flt3 mutation status in the Aur-A-high or Aur-A-low group. Flt3/WT indicates wild-type Flt3; ITD, Flt3 internal tandem duplication; TKD, the activation loop of the tyrosine kinase domain mutations. Error bars represent SEM.