Mothers Against Decapentaplegic Homolog 1 (Smad1)

 belongs to the SMAD, a family of proteins similar to the gene products of the Drosophila gene 'mothers against decapentaplegic' (Mad) and the C. elegans gene Sma. The name is a combination of the two. It was found that a mutation in the 'Drosophila' gene, MAD, in the mother, repressed the gene, decapentaplegic, in the embryo. The phrase "Mothers against" was added as a humorous approach since mothers often form organizations opposing various issues eg. This protein mediates the signals of the bone morphogenetic proteins, which are involved in a range of biological activities including cell growth, apoptosis, morphogenesis, development and immune responses. In response to BMP ligands, this protein can be phosphorylated and activated by the BMP receptor kinase.