E2F1 and colonic neoplasm: By analyzing 349 normal colon tissues and 275 colon cancer tissues in GEPIA online website, we found the mRNA expression levels of E2F1, E2F2, E2F3, E2F5, E2F7 and E2F8 were significantly higher in patients with colon cancer than normal control (P < 0.05) while E2F4 and E2F6 displayed no significant difference between colon cancer group and control group (P > 0.05) (Figs. 1A–1H).