Mothers against decapentaplegic homolog 3

Mothers against decapentaplegic homolog 3 also known as SMAD family member 3 or SMAD3 is a protein that in humans is encoded by the SMAD3 gene.

SMAD3 is a member of the SMAD family of proteins. It acts as a mediator of the signals initiated by the transforming growth factor beta (TGF-β) superfamily of cytokines, which regulate cell proliferation, differentiation and death.

Based on its essential role in TGF beta signaling pathway, SMAD3 has been related with tumor growth in cancer development.