CDK4 and acute myeloid leukemia: Our data also indicate that STAT5 targeting might be beneficial, since further FLT3 inhibitor escape routes like FLT3-TKD, BCL-2 family member upregulation, enhanced cell cycle progression through D-type cyclin, c-Myc and CDK4/6 action are also under STAT5 control in AML [44,45].