TGFB1 and neoplasm: TGF-β signaling has a predominant role in suppressing growth of normal epithelial cells, while promotes metastasis in many tumor cells, in part through tightly controlling the process of EMT.10 TGF-β activates Smads by binding to type II and type I serine-threonine kinase receptors (TβRII and TβRI), respectively.