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. Author manuscript; available in PMC: 2023 Mar 1.
Published in final edited form as: Cell Metab. 2022 Feb 4;34(3):355–377. doi: 10.1016/j.cmet.2022.01.007

Figure 6. Increased demand for nitrogen.

Figure 6.

Nitrogen-saving strategies used by transformed cells to mitigate the deficit of reduced nitrogen carriers in the tumor microenvironment. (A) De novo glutamine synthesis; (B) Preference for transamination of glutamate to α-ketoglutarate as a strategy to maximize non-essential amino acid synthesis in proliferating cells; (C) De novo glutamate synthesis; (D) Preference for CPS-I-mediated route of carbamoyl-phosphate production in LKB1-deificient tumors; (E) Increased availability of aspartate for pyrimidine synthesis coupled to an increased reliance on arginine import in ASS1-deficient tumors. GLUL; glutamate-ammonia ligase (glutamine synthetase); GDH1, glutamate dehydrogenase 1; CAD, carbamoyl-phosphate synthetase 2, aspartate transcarbamylase, and dihydroorotase; CPS-I, carbamoyl phosphate synthetase I; ASS1, argininosuccinate synthetase 1.