Previous studies have found that abnormally frequent methylation of genes with crucial roles in regulating the cell cycle, cell death, DNA damage repair, cell proliferation, invasion, and metastasis are associated with HCC, such as RASSF1, adenomatous polyposis coli (APC), cyclin-dependent kinase inhibitor 1 A (CDKN1A), and cadherin-1 (CDH1) [45, 47, 48]. The gene discussed is CDKN1A; the disease is hepatocellular carcinoma.