Overexpression of HDAC5 in HCC cells was correlated with reduced expression of p21 and hyperactivation of cyclin D1 and cyclin-dependent kinase 2/4/6 (CDK2/4/6), indicating that HDAC5 promotes cell cycle progression and blocks apoptosis in HCC tumorigenesis (60). The gene discussed is CCND1; the disease is hepatocellular carcinoma.