FLT3 and cancer: A674563 significantly affected the auto-phosphorylation of FLT3-ITD at the Y589/591 site in these intact cancer cell lines starting from 5 μM but potently inhibited the phosphorylation of STAT5, a downstream mediator of FLT3 signaling, as well as the expression of c-MYC starting from 0.5 μM concentration.