Regulatory immune cells, including Tregs, myeloid-derived suppressor cells (MDSCs), and M2-polarized tumor-associated macrophages (TAMs), further shape this suppressive ecosystem by producing inhibitory cytokines (e.g., TGF-β, IL-10) and depleting key metabolic substrates required for TIL fitness (119, 181). The gene discussed is TGFB1; the disease is neoplasm.