PTTG1 and hepatocellular carcinoma: Among the 22 hub genes, the up-regulated 17 genes (APSM, AURKA, CCNA2, CCNB2, CDC20, FEN1, FOXM1, HMMR, KIF20A, MELK, NCAPG, OIP5, PRC1, PTTG1, TOP2A, TPX2 and TRIP13) were correlated with the shorter OS of patients with HCC (Figure 4); while the other 5 hub genes were not correlated with the OS of patients with HCC.