As cancer cells with elevated E2F1 activity have been shown to be sensitive to HDAC inhibitor‐induced cell death (Zhao et al., 2005) and RB1 inactivation in RB results in deregulated E2F1 activity, several studies have investigated the effects of HDAC inhibitors on RB cell death (Dalgard et al., 2008; Karasawa and Okisaka, 2004; Poulaki et al., 2009). Here, HDAC9 is linked to cancer.