The first step in signalling through the transforming growth factor (TGF)-β pathway involves phosphorylation of either Smad2 or Smad3 by an activated type-I receptor kinase. How do TGF-β, the receptor and the Smad manage to meet up? The answer is a newly discovered ‘anchor’ protein termed SARA, which recruits the Smads to the TGF-β receptor.
- Peter ten Dijke
- Carl-Henrik Heldin