| Smad proteins belong to a group of intracellular signal transducers and downstream effectors of TGF-β/BMP Signaling. The family consists of nine members that are highly conserved in the N- and C-terminal regions. Smad3 is a key component in intracellular signaling of transforming growth factor beta (TGF-β), an inhibitor for tumor cell proliferation. Smad3 is activated by activin/TGF-β receptors, which form a heteromeric complex with Smad4, translocating to the nucleus and regulating the expression of TGF- β target genes. Interaction of Smad3 with Akt, can initiate TGF- β induced apoptosis and cell cycle arrest. Smad3 expression may be critical in tumor suppression in early stages of gastric carcinogenesis. |
