TGFB1 and neoplasm: Furthermore, tumor cells synthesized TGFβ acts indirectly on stromal cells by stimulating the production of growth and mitogenic factors, such as platelet-derived growth factor (PDGF), and inducing the trans-differentiation of stromal progenitors such as fibroblasts, endothelial cells, bone marrow-derived mesenchymal stem cells (MSCs) into “activated fibroblasts” (66–68).