Fig. 4

Amino acid competition in the TME. T cells compete with macrophages, MDSCs, and tumor cells for several amino acids, which influence the anti-tumor functions of T cells. Moreover, these cells produce kynurenine to suppress T cells, emphasizing the complexity of amino acid metabolism in the TME. The dashed line represents two lines that do not intersect. The arrow line represents activation and the line with a bar at the end represents inhibition. AHR Aryl hydrocarbon receptor; Arg Arginine; Arg1/2 Arginase-1/2; DC Dendritic cell; IDO Indoleamine 2,3-dioxygenase; iNOS Inducible isoform of NO synthase; Kyn Kynurenine; MDSC Myeloid-derived suppressor cell; Met Methionine; MTA Methylthioadenosine; PD-1 Programmed death 1; SAM S-adenosylmethionine; STAT5 Signal transducer and activator of transcription 5; TAM Tumor-associated macrophages; Trp Tryptophan