Growing evidence demonstrates that HDACs are overexpressed in a variety of primary human tumors [25], including breast cancer, and we also found that higher levels of specific HDACs are associated with a significantly poorer outcome in patients with either breast cancer (Supplementary Fig. 1a) or lung cancer (Supplementary Fig. 1b), justifying the potential use of HDAC inhibitors (HDACi) in cancer therapy. The gene discussed is HDAC9; the disease is breast carcinoma.