High FLT3/ITD mutant-to-wild-type ratio correlates with increased sensitivity to FLT3 inhibition by CEP-701. Dot plot showing cytotoxic response of FLT3/ITD samples to 100-nM CEP-701 stratified by ITD/WT ratio. “Low” ratios were those less than the mean ITD/WT ratio for the sample set (0.721). “High” ratios were those greater than the mean. P value is from Student t test. Error bars represent standard error of the mean (SEM).