HDAC9 and neoplasm: It is a selective inhibitor of histone deacetylase (HDAC) and has been shown to have potent anti-angiogenic activity and reduce the level of hypoxia inducible factor-1α (HIF-1α) in human and mouse tumor cell lines.295,296 In the HCT-116 xenograft tumor model of human colon cancer, Apicidin inhibited tumor growth.