S727 phosphorylation of STAT3 has also been found to be constitutive in hematological malignancies (e.g., B-cell derived tumors and pediatric acute myeloid leukemia) [9,10]; however the only oncogenes that we are aware of that lead to S727 but not Y705 phosphorylation belong to the Ras family. Here, STAT3 is linked to acute myeloid leukemia.