HOXA9 and acute myeloid leukemia: Nussenzweig and Hess's groups found that Kmt2d deficiency prevents the MLL‐AF9‐ or HOXA9‐driven AML formation in mice.[26, 27] They further illustrated that Kmt2d deficiency induced myeloid differentiation in MLL‐AF9 leukemic blasts, suggesting a tumor‐promoting role of Kmt2d.