The mechanism by which tumor nests restrict T lymphocyte infiltration may be related to the production of dense collagen and hyaluronic acid by CAFs, as well as the secretion of inhibitory cytokines such as TGF-β and CXCL12, and T cells are confined to the matrix to prevent their accumulation near cancer cells, thereby inhibiting anti-tumor immunity [68]. The gene discussed is TGFB1; the disease is cancer.