GLUD1 and neoplasm: On the other hand, it is known that glutamine is absorbed by tumor cells [6,28] and metabolized within the mitochondria via two deamination steps: (1) production of glutamate by glutaminase (GLS1/GLS2) through an irreversible reaction, (2) production of α-KG by glutamate dehydrogenase (GLUD1) [15].