TKTL1 and hepatocellular carcinoma: The GSEA analysis showed that the highly expressed PPFIA4, SAP30, and TKTL1 in the ceRNA regulatory axes were all significantly enriched in a variety of hypoxia-and cancer-related pathways (Figure 7A–C), such as DNA repair, E2F target gene, G2/M checkpoint and PI3K/AKT/mTOR pathway, indicating that hypoxia-related genes PPFIA4, SAP30, TKTL1 were closely related with tumor microenvironment and HCC development.