ARID2 deficiency precipitates G1/S phase acceleration via upregulated CCND1/CCNE1 expression, CDK4 activation and retinoblastoma (Rb) hyperphosphorylation; (2) ARID2 loss impairs nucleotide excision repair (NER) pathway fidelity, exacerbating DNA damage accumulation, mutagenic susceptibility and carcinogen sensitivity; (3) In HBV‐associated HCC, inverse correlation between ARID2 expression and HBx oncoprotein levels mechanistically links to HBx‐mediated suppression of ATOH1‐binding motifs in the ARID2 promoter—a regulatory axis potentiating viral hepatocarcinogenesis [72]. The gene discussed is CCND1; the disease is hepatocellular carcinoma.