Role and Mechanism of Smad Proteins in TGF-β Signal Transduction Pathway

Smad proteins possess special structure and property and play significant roles in TGF-β signal transduction pathway.TGF-β activates downstream Smad proteins,thus initiating intracellular signaling pathways via its interaction with TβR.There are three types of Smad proteins,including R-Smad,Co-Smad and I-Smad.Furthermore,the function of Smads is subject to the regulation mediated by many other cell factors and signaling pathways,leading to cross-talk in the TGF-β signaling pathway.