{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"SMAD4, also known as mothers against decapentaplegic homolog 4 (DPC4) or SMAD family member 4, belongs to the SMAD family. The SMAD family contains three functional classes: receptor-regulated SMADs (R-SMADs), co-SMADs, and inhibitory SMADs (I-SMADs). SMAD4 acts as a common partner (co-SMAD) for all R-SMADs and is essential for transducing signals for all transforming growth factor beta (TGF-β) superfamily members. SMAD4 forms complexes with R-SMADs, which are phosphorylated by receptor kinases upon ligand binding, and then the SMAD4/R-SMAD complex translocates to the nucleus to regulate gene transcription. TGF-β signaling pathway negatively regulates growth of epithelial cells and the extracellular matrix (ECM). SMAD 4 is not expressed by all cells and expression can be seen on skin, pancreatic, colon, uterus and epithelial cells. It is also produced by fibroblasts. SMAD4 is often found mutated in many cancers such as pancreatic and colorectal cancers. The mutation can be inherited or acquired during an individual’s lifetime."}]}]}