TGFB1 and neoplasm: In the tumor microenvironment, tumor and stromal cells upregulate various profibrotic growth factors such as transforming growth factor-β (TGF-β), platelet-derived growth factor (PDGF), and basic fibroblast growth factor (bFGF), all of which are main mediators for the transdifferentiation of stromal fibroblasts into CAFs (36, 37).