In one of these studies, inhibitors against HDAC for its antitumor activity and the underlying molecular mechanisms of such activity on MDA-MB-231 (231) human breast cancer cells have been examined, and the data from the study suggested that the HDAC inhibitor, namely IN-2001, is a novel promising therapeutic agent with potent antitumor effects against human breast cancers (Min et al., 2012). The gene discussed is HDAC9; the disease is breast cancer.