In a study evaluating the expression of HDAC1, HDAC2, HDAC6, and acetylated histone 4 (H4) in patients with lymphoma, HDAC1 was found to be overexpressed to a larger degree in patients with PTCL compared with patients with diffuse large B-cell lymphoma (Marquard et al., 2009). Here, HDAC1 is linked to lymphoma.