PLK1 and hepatocellular carcinoma: Considering that some of the hub genes have already been reported on and researched in HCC, such as NCAPG, TTK, TOP2A, CDC20, CDK1, and so on (Wong et al., 2009; Li et al., 2014; Liu et al., 2015; Wu et al., 2018; Zhang et al., 2018), we finally chose 13 hub genes (GTSE1, PLK1, NCAPH, SKA3, LMNB2, SPC25, HJURP, DEPDC1B, CDCA4, UBE2C, LMNB1, PRR11, and SNRPD2) on which little research had been done regarding HCC to continue our deeper exploration.