CD Markers

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CD Markers

CD9

Reviewers: Nat Pernick, M.D., (see Reviewers page)
Revised: 18 December 2010, last major update December 2010
Copyright: (c) 2002-2010, PathologyOutlines.com, Inc.

General
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● Cell surface protein that mediates various signal transduction events

Terminology
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● Also called motility related protein 1 (MRP1)

Physiology
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● Member of transmembrane 4 superfamily (tetraspanin family); tetraspanins have 4 hydrophobic domains, organize multimolecular complexes in the plasma membrane; each tetraspanin associates specifically with integrins and other tetraspanins, forming primary complexes and leading to a molecular network of interactions, the "tetraspanin web"
● Regulates cell motility, development, activation, growth and adhesion (Blood 2010 Nov 9 [Epub ahead of print])
● Regulates paranodal junction formation (between neurons and glia)
● Oocyte CD9 is required for sperm-egg fusion
● Required for microparticle release from coated-platelets (Platelets 2009;20:361); triggers platelet activation and aggregation
● Supports myotube maintenance and promotes muscle cell fusion

Diagrams
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Structure

Clinical features
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● Antibodies are used to purge bone marrow in acute lymphoblastic leukemia prior to peripheral stem cell bone marrow transplant (Am J Pediatr Hematol Oncol 1993;15:162)
● Downregulation in ovarian carcinoma may promote tumor dissemination (Cancer Res 2005;65:2617)
● Presence in small cell lung cancer may mediate chemoresistance (Cancer Res 2010;70:8025)
● Expression is associated with poor prognosis in gastric carcinoma (Pathol Res Pract 2010;206:607)

Uses by pathologists
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● No significant clinical use by pathologists

Micro images
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Normal tissue

Vascular endothelium

Cervical squamous epithelium

Normal cerebrum

Various tumors

Cervical carcinoma

Various CNS non-neuroepithelial tumors

Various images

Positive staining (normal)
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● Pre B cells, B cell subset, activated T cells, basophils, eosinophils, macrophages, megakaryocytes, plasma cells, 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)
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● Pre-B ALL, AML-M3, astrocytoma (J Histochem Cytochem 2002;50:1195)
● Vascular tumors: angiosarcoma, juvenile nasopharyngeal angiofibroma, Kaposi’s sarcoma (Mod Path 2003;16:1028)

Negative staining
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● Red blood cells, renal collecting duct carcinomas (almost all)

Additional references
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● MIM 143030

End of CD Markers > CD9

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