While most of the tested HDAC genes are expressed in all AML cell lines, the expression levels of HDAC1 and HDAC3 (class I HDACs) but also HDAC4, HDAC5, and HDAC9 (class IIA HDACs), and HDAC10 (class IIB HDAC) are highly expressed in MOLM-13, MOLM-14, as well as in MV4-11 cells. This evidence concerns the gene HDAC9 and acute myeloid leukemia.