TGFB1 and cancer: Notably, although TGF-β does not share or compete for receptors with BMPs, both strongly induce phosphorylation of Smad1/5/8 in many different cell types, including fibroblasts, endothelial cells, epithelial cells, and epithelium-derived cancer cells.150–154 Despite this common phosphorylation event, TGF-β cannot induce BMP-like transcriptional responses.