HDAC9 and diffuse large B-cell lymphoma: Besides, abnormal expression of HDACs has been found in hematological cancers, including DLBCL [21–23], and several HDAC inhibitors, such as vorinostat (chemically named SAHA), romidepsin, panobinostat (also called LBH589) and belinostat, have been approved for the clinical treatment of hematologic cancers [24].