HDAC9 and diffuse large B-cell lymphoma: Most therapeutic strategies for hematologic cancers, including T-cell acute lymphoblastic leukemia (Hales et al., 2014), acute myeloid leukemia (Li et al., 2019), chronic lymphocytic leukemia, small lymphocytic lymphoma (Blair, 2018), diffuse large B-cell lymphoma (DLBCL) (Kalac et al., 2011), cutaneous T-cell lymphoma (West and Johnstone, 2014), and others, involve regulation of PI3K/AKT/mechanistic target of rapamycin (mTOR) and HDAC pathways (Yoon and Eom, 2016).