Hurst et al. (2008) showed that E2F3 inhibited pRb and P53 through two important pathways of cell proliferation regulation and tumor monitoring, p16(Ink4a)-cycd/cdk4-rb-e2f and Arf/mdm2-p53, respectively, leading to the disorder of cell cycle regulation and thus promoting the occurrence and development of tumors. Wang, Zhao & Yuan (2011) found that the expression of E2F3 was high in colorectal carcinoma. Here, CDK4 is linked to colorectal carcinoma.