ABCG2 and cancer: The top 10 significantly enriched KEGG metabolic pathways according to the differential abundance score were biosynthesis of amino acids, glycerophospholipid metabolism, d-amino acid metabolism, ABC transporters, histidine metabolism, central carbon metabolism in cancer, alanine, aspartate, and glutamate metabolism, protein digestion, absorption, aminoacyl-tRNA biosynthesis, and choline metabolism in cancer (Figure 5E).