Among them, the expression of three upregulated MAPK signaling pathway-related genes, PGF, artemin (ARTN) and calcium voltage-gated channel subunit alpha1 E (CACNA1E), but not the two downregulated genes nuclear receptor subfamily 4 group A member 1 (NR4A1) and colony stimulating factor 1 receptor (CSF1R), are significantly associated with reduced overall survival rates of liver cancer patients (Figure 6A; Supplementary Table S8). Here, PGF is linked to liver cancer.