RB1 and viral infectious disease: The RB gene is one of the most important tumor suppressor genes (TP53, RB, PTEN), which regulates the cell division cycle.133,134 RB protein binds to EBV protein E7, which leads to protein degradation with E2F release and infinite cell proliferation.135 When p53 protein is activated by virus infection or DNA damage, the downstream signal p21 is upregulated, which results in RB-E2F complex (RB, E2F, and dimerization partners) formation and cell cycle gene downregulation.