MYC and acute myeloid leukemia: However, in the FLT3 wild-type (wt) expressing cell lines, OCI-AML-3 and U937, phosphorylation of FLT3 Y589/591 were not detected and phosphorylation of STAT5 as well as cMyc expression were unaffected, except the AKT kinase mediated signaling pathway (Supplementary Figure 4).