Compared to the low-expression group of HCC patients, those with high expression levels of CCNB1 (P = 0.015), CDK4 (P = 0.023), CDK1 (P = 0.00081), and PLK1 (P = 0.00074) proteins had a lower overall survival rate (Fig. 7E-H). This evidence concerns the gene PLK1 and hepatocellular carcinoma.