In the development of acute promyelocytic leukemia and acute myeloid leukemia, for example, fusion proteins like promyelocytic leukemia-retinoic acid receptor alpha (PML-RARα), Promyelocytic leukemia zinc finger-retinoic acid receptor alpha (PLZF-RARα), and acute myeloid leukemia-eight twenty-one (AML1-ETO) recruit HDAC-containing repressor complexes that suppress genes essential for myeloid differentiation [49]. This evidence concerns the gene HDAC9 and acute promyelocytic leukemia.