SLC15A1 and neoplasm: An oxidative metabolic profile is superior to a glycolytic metabolic state during cell culture, as it culminates in T cell progeny with superior anti-tumor function.25, 26, 27 To distinguish between an intracellular versus extracellular benefit of carnosine, we included Gly-Sar to competitively inhibit carnosine uptake via the cell surface transporter PEPT1.