SMAD3 (UniProt/Swiss-Prot entry P84022) belongs to the SMAD (‘mothers against decapentaplegic) family of proteins which are
signal transducers and transcriptional modulators involved in multiple pathways. SMAD3 is activated by TGF-beta (transforming
growth factor) and activin type 1 receptor kinases which phosphorylates the C-terminal serines 423 and 425. SMAD3 binds
the TRE element in the promoter region of many genes that are regulated by TGF-beta and is involved in chondrogenesis,
osteogenesis and wound healing. It is also thought to play a role in carcinogenesis.