CDK4 and hepatocellular carcinoma: Xing et al. (2020) reported that in HCC cells, haprolid upregulates the expression of p21 and p27 and inhibits the G1/S phase transition of cells, which may be related to the downregulation of Rb/E2F expression. Therefore, it can be speculated that CENPN reduces the level of phosphorylated Rb and inhibits E2F1 transcription by downregulating the activities of the p27-CDK4/cyclin D1 and p21-CDK2/cyclin E axes, thus inhibiting c-myc as well as cyclin E, inhibiting cell proliferation, and ultimately affecting the prognosis of liver cancer (Fig. 8G).