ABCG2 and amyotrophic lateral sclerosis: Both CARs and FFAs were the major up-regulated DEMs in old CRs and included carnitine C18: 3, carnitine C20: 2, hexadecanoic acid (C16: 0), palmitoleic acid (C16: 1), and cis-11,14-eicosadienoic acid (C20: 2), which were enriched in the arginine biosynthesis, ABC transporter, amyotrophic lateral sclerosis, and biosynthesis of amino acid pathways.