GPT and neoplasm: Tumor cells transport glutamine into cells through specific transporters, and then convert it into glutamate under the action of glutaminase (AST, ALT and Phosphoserine Aminotransferase 1), and further convert it into α-ketoglutarate (α-KG), which enters the Tricarboxylic Acid cycle (TCA) and participates in the onset, development and dissemination of tumors (19, 20).