HDAC9 and cancer: The first successful HDAC inhibitor bearing hydroxamic acid moiety, Vorinostat (SAHA, suberanilohydroxamic acid, Zolinza ®) (1) [78,79], was successfully used in the treatment of cutaneous T-cell lymphoma and its further analogues Belinostat (peripheral T-cell lymphoma), Panbinostat (multiple myeloma), and other types of HDAC inhibitors: Romidepsin (cutaneous T-cell lymphoma) and Chidamide (peripheral T-cell lymphoma) were approved by the FDA for cancer treatment [80].