CDKN1A and hepatocellular carcinoma: p53 can activate p21, growth arrest, and the DNA damage-inducible protein GADD45 alpha, etc. to stop the HCC cell cycle; it can also upregulate apoptotic protease-activating factor 1, BAX, Fas, etc. to encourage apoptosis in HCC cells; it can also promote angiogenesis by upregulating thrombospondin-1, etc.; it can also increase the activity of 5′-AMP-activated protein kinase subunit beta-1, Bcl2 binding component 3 (PUMA), etc. to encourage autophagy; as well as can activate DNA damage-binding protein 2, fanconi anemia group C protein, etc. to promote DNA repair.