RRM2 and hepatocellular carcinoma: High expressions of CDK1 (P = 1.1e-5), CCNB1 (P = 3.4e-5), TOP2A (P = 0.0001), CCNA2 (P = 0.0002), PRC1 (P = 0.0002), RRM2 (P = 5.5e-5), CDKN3 (P = 0.0066), and CCNB2 (P = 0.0013) were associated with poor OS in HCC patients (Fig. 4).