TOP2A and hepatocellular carcinoma: The M1 module was strongly associated with cell cycle-related functions and contained 22 hub genes, for example, FEN1B, BIRC5, UBE2T, NEK2, CDKN3, TTK, CCNB1, and TOP2A. This is confirmed by an HCC-associated network proposed by Xing et al. [74], which was derived from five studies in HCC.