By targeting different substrate molecules, Rad18 induces radioresistance formation in various tumors such as glioma, hepatocellular carcinoma, and esophageal carcinoma, suggesting that Rad18 may be a key mediator in REV1 regulating downstream gene expression and exerting function [28, 29, 36, 37]. The gene discussed is REV1; the disease is hepatocellular carcinoma.