HOXA9 and acute myeloid leukemia: Nevertheless, as HOXA9 is most consistently induced in murine and human AMLs and correlates most highly with poor prognosis [4–6], as absence of HoxA9 prevents transformation by MLL-ENL [32], and as HOXA9 depletion is sufficient to induce proliferation arrest and apoptosis in AML cell lines and in primary AML cells [10], HOXA9 may be the HOXA transcription factor most critical for normal and malignant myelopoiesis.