HDAC9 and acute myeloid leukemia: Taken together, these observations suggest that the combination of RARA/RXRA agonists and HDAC antagonists should be further explored in human AML, possibly as a part of combination therapy also including other targeted therapies, e.g., demethylating agents, KDM1A inhibitors, MECOM inhibitors, cytarabine, CD38 molecule (CD38) targeting or even BCL2 antagonists [13].