GLS and neoplasm: Proteins that play an important role in this glutamine metabolic pathway are amino acid transporter-2 (ASCT2), which is involved in the intracellular transport of glutamine consumed by tumor cells, glutaminase 1 (GLS1), an enzyme that converts glutamine to glutamate, and glutamate dehydrogenase (GDH), which converts glutamate into α-ketoglutarate to affect the TCA cycle [6–8].