These pathways include “ABC transporters,” “aldosterone-regulated sodium reabsorption,” “caffeine metabolism,” “mineral absorption,” “neuroactive ligand–receptor interaction,” “phenylalanine, tyrosine, and tryptophan biosynthesis,” “protein digestion and absorption,” “prostate cancer,” “synaptic vesicle cycle,” and “intestinal immune network for IgA production.” Among these pathways, the one with the highest impact score was “intestinal immune network for IgA production,” and the associated differential metabolite was identified as all-trans retinoic acid (ATRA), also known as Tretinoin. This evidence concerns the gene ABCG2 and prostate cancer.