HDAC9 and prostate carcinoma: Compared with the hydroxamic acid SAHA (IC50 = 20 nM), the mainstay of HDAC-targeting anticancer therapy, the pan-HDAC-inhibitory potency of the novel compounds is distinctly weaker, yet still in a clinically meaningful range (Figure 4a) [12].Their HDAC-inhibitory efficacy was further evaluated in prostate cancer cells by immunodetection of the increased portion of acetylated histone H3, which is part of the cellular nucleosome.