HDAC9 and cancer: Based on the anti-leukemic activities observed with single agent and combination treatment shown above and the fact that HDAC inhibitors and azacitidine can induce re-expression of certain tumor suppressor genes silenced through epigenetic mechanisms in cancer [62, 65–70], we focused on category G, which includes genes up-regulated by each single agent and further up-regulated by the combination, for further validation.