Turning off Smads: Identification of a Smad Phosphatase

Although the activation of Smad signaling pathways downstream of TGF-β superfamily ligands by receptor-mediated Smad phosphorylation is well understood, nothing is known about Smad phosphatases that turn off Smad activity. Recently in Genes & Development, Chen et al. (2006) describe pyruvate dehydrogenase phosphatase as a Smad1 phosphatase that functions in Drosophila in the Decapentaplegic pathway and in mammalian cells in the BMP pathway