Mothers against decapentaplegic homolog 9

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AliasesSMAD9, MADH6, MADH9, PPH2, SMAD8, SMAD8A, SMAD8B, SMAD8/9, SMAD family member 9
External IDsOMIM: 603295 MGI: 1859993 HomoloGene: 21198 GeneCards: SMAD9
Gene location (Human)
Chromosome 13 (human)
Chr.Chromosome 13 (human)[1]
Chromosome 13 (human)
Genomic location for SMAD9
Genomic location for SMAD9
Band13q13.3Start36,844,831 bp[1]
End36,920,765 bp[1]
RefSeq (mRNA)



RefSeq (protein)



Location (UCSC)Chr 13: 36.84 – 36.92 MbChr 3: 54.76 – 54.8 Mb
PubMed search[3][4]
View/Edit HumanView/Edit Mouse

Mothers against decapentaplegic homolog 9 also known as SMAD9, SMAD8, and MADH6 is a protein that in humans is encoded by the SMAD9 gene.[5]

SMAD9, as its name describes, is a homolog of the Drosophila gene: "Mothers against decapentaplegic". It belongs to the SMAD family of proteins, which belong to the TGFβ superfamily of modulators. Like many other TGFβ family members, SMAD9 is involved in cell signalling. When a bone morphogenetic protein binds to a receptor (BMP type 1 receptor kinase) it causes SMAD9 to interact with SMAD anchor for receptor activation (SARA).The binding of ligands causes the phosphorylation of the SMAD9 protein and the dissociation from SARA and the association with SMAD4. It is subsequently transferred to the nucleus where it forms complexes with other proteins and acts as a transcription factor. SMAD9 is a receptor regulated SMAD (R-SMAD) and is activated by bone morphogenetic protein type 1 receptor kinase. There are two isoforms of the protein. Confusingly, it is also sometimes referred to as SMAD8 in the literature.


The SMAD proteins are homologs of both the drosophila protein, mothers against decapentaplegic (MAD) and the C. elegans protein SMA. The name is a combination of the two. During Drosophila research, it was found that a mutation in the gene, MAD, in the mother, repressed the gene, decapentaplegic, in the embryo. The phrase "Mothers against" was added since mothers often form organizations opposing various issues e.g. Mothers Against Drunk Driving or (MADD); and based on a tradition of such unusual naming within the gene research community.[6]


  1. ^ a b c GRCh38: Ensembl release 89: ENSG00000120693 - Ensembl, May 2017
  2. ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000027796 - Ensembl, May 2017
  3. ^ "Human PubMed Reference:".
  4. ^ "Mouse PubMed Reference:".
  5. ^ Watanabe TK, Suzuki M, Omori Y, Hishigaki H, Horie M, Kanemoto N, Fujiwara T, Nakamura Y, Takahashi E (June 1997). "Cloning and characterization of a novel member of the human Mad gene family (MADH6)". Genomics. 42 (3): 446–51. doi:10.1006/geno.1997.4753. PMID 9205116.
  6. ^ "Sonic Hedgehog, DICER, and the Problem With Naming Genes", Sep 26, 2014, Michael White.