ABCG2 and cancer: KEGG pathway enrichment analysis indicated that these differential metabolites were significantly enriched in multiple pathways, including ABC transporters, protein digestion and absorption, central carbon metabolism in cancer, biosynthesis of plant secondary metabolites, aminoacyl-tRNA biosynthesis, arginine biosynthesis, alanine, aspartate, and glutamate metabolism, and proximal tubular bicarbonate reclamation (Supplementary Figure S4).