Using univariate and multivariate Cox regression analysis, we analyzed the prognostic value of the methylation status and expression levels of the five aforementioned genes in HCC (Figure 1d, e), and obtained a gene signature, comprised of four genes, namely RRM2, FTCD, CYP2C9, and ATP6V1C1, that was strongly associated with HCC prognosis (P < 0.05). This evidence concerns the gene RRM2 and hepatocellular carcinoma.