TGFB1 and neoplasm: In contrast, some tumor stromal cells, such as M2-type tumor-associated macrophages, cancer-associated fibroblasts, and myeloid-derived suppressive cells, possess immunosuppressive properties; these cells inhibit the antitumor immune response, either by releasing immunosuppressive cytokines, such as IL-10 and transforming growth factor-beta (TGF-β), or by directly inhibiting CTL cytolytic activity through cell surface expression of coinhibitory molecules, such as PD-L1 and TIGIT [6, 7].