The results showed that the mRNA expression levels of CCNB1 (P = 0.00015), CDK4 (P = 0.0021), CDK1 (P = 0.00017), and PLK1 (P = 0.00082) were negatively correlated with the overall survival rate of HCC patients (Fig. 7I-L). This evidence concerns the gene PLK1 and hepatocellular carcinoma.