The two cleavages thus generate the 65-nucleotide pre-miRNA composed of the 22 bp (two helical turns) of dsRNA and the top loop.

TLS Online TPP Program

#Id: 9368

#Unit 4. Cell Communication and Cell Signaling

Smad4 was originally called DPC (deleted in pancreatic cancer)

TLS Online TPP Program

#Id: 9369

#Unit 4. Cell Communication and Cell Signaling

Negative regulators of TGF-β signaling are induced by TGF-β signaling (Example of Negative feedback): 

Ski 

SnoN 

I-Smads (Smad7)

TLS Online TPP Program

#Id: 9370

#Unit 4. Cell Communication and Cell Signaling

SnoN and Ski trigger abnormal cell proliferation by blocking the Smad-complex.

TLS Online TPP Program

#Id: 9371

#Unit 4. Cell Communication and Cell Signaling

TLS Online TPP Program

#Id: 9372

#Unit 4. Cell Communication and Cell Signaling

Ski recruits N-CoR, which binds directly to mSin3A; mSin3A interacts with HDAC, that promotes histone deacetylation on nearby promoters, repressing gene expression

TLS Online TPP Program

#Id: 9373

#Unit 4. Cell Communication and Cell Signaling

Smad7 binds to the activated RI receptors and blocks its ability to phosphorylate Smad2 or Smad3.