TGFB1 and neoplasm: TGF-β can stimulate tumor progression even when its signaling pathways are unavailable in the tumor cells, indicating its additional tumor-promoting effects exerted on tumor stroma.760–764,843 Fibroblasts, endothelial cells, and immune cells are the major stromal cell types in TME and can all be manipulated by TGF-β in favor of tumor progression.