Reviewer: Nat Pernick, M.D. (see Reviewers page)
Revised: 24 August 2013, last major update August 2013
Copyright: (c) 2002-2013, PathologyOutlines.com, Inc.
PubMed Search: CD9[title]
- Member of transmembrane 4 superfamily (tetraspanin family); tetraspanins have 4 hydrophobic domains, organize multimolecular complexes in plasma membrane; each tetraspanin associates specifically with integrins and other tetraspanins, forming primary complexes and leading to molecular network of interactions, the "tetraspanin web"
- Regulates cell motility, development, activation, growth and adhesion (Blood 2011;117:1840), differentiation (OMIM #143030), fertilization (oocyte CD9 is required for sperm-egg fusion)
- Regulates paranodal junction formation (between neurons and glia)
- Required for microparticle release from coated-platelets (Platelets 2009;20:361); triggers platelet activation and aggregation
- Supports myotube maintenance and promotes muscle cell fusion
- Downregulation in ovarian carcinoma may promote tumor dissemination (Cancer Res 2005;65:2617)
- May suppress metastasis in small cell lung cancer by promoting apoptosis via calretinin expression (Cancer Res 2010;70:8025, FEBS Open Bio 2013;3:225)
- May mediate invasion by upregulating MMP9 (PLoS One 2013;8:e67766)
Uses by pathologists
- No significant clinical use by pathologists
Positive staining - normal
- Pre B cells, B cell subset, activated T cells, basophils, eosinophils (Am J Respir Cell Mol Biol 2012;46:188), macrophages, megakaryocytes, plasma cells, plasma cell precursors in germinal centers (Biochem Biophys Res Commun 2013;431:41), platelets
- Brain, cardiac muscle, GI system, kidney (glomeruli, tubules and collective ducts), liver, lymphatic epithelium, ovarian surface epithelium, peripheral nerve, skin, spleen, thyroid, tonsil
Positive staining - disease
- Red blood cells, renal collecting duct carcinomas (almost all)
End of CD Markers > CD9
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