CDKN2A and hepatocellular carcinoma: TGF-β is able to induce NADPH oxidase 4 (Nox4)-dependent, p21 (Cip1)-dependent, p15 (Ink4b)-dependent, and ROS-dependent—but not p53- and p16 (Ink4a)-dependent—senescence arrest in well-differentiated hepatocellular carcinoma (HCC) cells [9].