HDAC9 and cancer: HDACs support cell growth for multiple tumor cells, including diffuse large B cell lymphoma, lung adenocarcinoma, and breast cancer (Gupta et al., 2012; Lapierre et al., 2016; Wang et al., 2016); therefore, HDAC inhibitors are clinically used for cancer treatment (Khan and La Thangue, 2012; Li and Seto, 2016).