→ SMAD3|T179_pho|S204_pho|S208_pho|S213_pho|S423_pho|S425_pho@Cytosol References
PMID:10197981
PMID:12193595
PMID:16156666
Erk kinases phosphorylate Smad2 and Smad3 at specific sites in the region linking the DNA-binding domain and the transcriptional activation domain.
These sites are separate from the TGFB receptor phosphorylation sites that activate Smad nuclear translocation.
Feedback loop: TGFB activates Ras/Raf/Mek/Erk signaling (PMID:17673906) and Erk reduces TGFB/Smads transcriptional activity.
PMID:15241418
Feedback loop
CDK phosphorylation of Smad3 on Thr8/Thr179/Ser213 inhibits its transcriptional activity and antiproliferative function.
Because cancer cells often contain high levels of CDK activity, diminishing Smad3 activity by CDK phosphorylation may contribute to tumorigenesis and TGFB- resistance in
cancers.