HDAC9 and cancer: In addition to suberoylanilide hydroxamic acid (SAHA), and Romidepsin (FK228), approved by the U.S. Food and Drug Administration (FDA) for the treatment of cutaneous T-cell lymphoma in 2006 and 2009, respectively, there are at least 15 different HDAC inhibitors currently undergoing clinical trials in patients with a wide range of different cancers either as monotherapy or in combination therapy [107,109].