FLT3 and acute myeloid leukemia: Furthermore, AML cells often have FLT3-ITD, FLT3-tyrine kinase and SCF receptor mutations that initiate constitutive downstream signaling with STAT5 activation; most patients with t(6;9) AML show additional FLT3-ITDs that possibly also contribute to the STAT5 activation observed in these AML cells [109].