GCG and cancer: In addition, the KEGG pathway enrichment analysis demonstrated that the 8 metabolites were mainly enriched in HIF-1 signaling pathway, pyruvate metabolism, cAMP signaling pathway, glucagon signaling pathway, glycolysis/gluconeogenesis, central carbon metabolism in cancer, propanoate metabolism, glycine, serine, and threonine metabolism and aminoacyl-tRNA biosynthesis (Supplementary Fig. S7A).