Inhibitory effect of FF-10101 on drug-resistant FLT3 mutations. (A) 32D transfectants stably expressing wild-type FLT3 or mutated FLT3s were treated with FF-10101 or quizartinib for 2 days. After treatment, cell viability was assessed by MTS assay. Three independent experiments were performed, and mean ± standard error of IC₅₀ values of cell viability for each cell lines are shown in this graph. (B) 32D transfectants were treated with FF-10101 or quizartinib for 2 hours. Cell lysates were prepared and subjected to western blot analysis to assess the inhibitory effect of FF-10101 on phosphorylation of mutant FLT3.