Classes
There are three classes of SMAD:
- The receptor-regulated Smads (R-SMAD) which include SMAD1, SMAD2, SMAD3, SMAD5 and SMAD8/9
- The common-mediator Smad (co-SMAD) which includes only SMAD4, which interacts with R-SMADs to participate in signaling
- The antagonistic or inhibitory Smads (I-SMAD) which include SMAD6 and SMAD7, which block the activation of R-SMADs and Co-SMADs.
Read more about this topic: SMAD (protein)
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