Keratin 20

'''Keratin 20''', often abbreviated '''CK20''', is a protein that in humans is encoded by the ''KRT20'' gene.<ref name="pmid8359595">{{cite journal |vauthors=Moll R, Zimbelmann R, Goldschmidt MD, Keith M, Laufer J, Kasper M, Koch PJ, Franke WW | title = The human gene encoding cytokeratin 20 and its expression during fetal development and in gastrointestinal carcinomas | journal = Differentiation | volume = 53 | issue = 2 | pages = 75–93 |date=June 1993 | pmid = 8359595 | doi = 10.1111/j.1432-0436.1993.tb00648.x}}</ref><ref name="pmid12515621">{{cite journal |vauthors=Ye X, Li Y, Hou G, Liu Z, Chen T | title = [Significance of cytokeratin gene (CK-20 mRNA) expression in metastatic lymph nodes in colon carcinoma patients] | language = zh | journal = Zhonghua Zhong Liu Za Zhi | volume = 24 | issue = 3 | pages = 261–3 |date=May 2002 | pmid = 12515621 }}</ref><ref name="pmid16831889">{{cite journal |vauthors=Schweizer J, Bowden PE, Coulombe PA, Langbein L, Lane EB, Magin TM, Maltais L, Omary MB, Parry DA, Rogers MA, Wright MW | title = New consensus nomenclature for mammalian keratins | journal = J. Cell Biol. | volume = 174 | issue = 2 | pages = 169–74 |date=July 2006 | pmid = 16831889 | pmc = 2064177 | doi = 10.1083/jcb.200603161 }}</ref>

Keratin 20 is a type I cytokeratin. It is a major cellular protein of mature enterocytes and goblet cells and is specifically found in the gastric and intestinal mucosa.<ref name="pmid1696264">{{cite journal |vauthors=Moll R, Schiller DL, Franke WW | title = Identification of protein IT of the intestinal cytoskeleton as a novel type I cytokeratin with unusual properties and expression patterns | journal = J. Cell Biol. | volume = 111 | issue = 2 | pages = 567–80 |date=August 1990 | pmid = 1696264 | pmc = 2116178 | doi = 10.1083/jcb.111.2.567}}</ref>

In immunohistochemistry, antibodies to CK20 can be used to identify a range of adenocarcinoma arising from epithelia that normally contain the CK20 protein. For example, the protein is commonly found in colorectal cancer, transitional cell carcinomas and in Merkel cell carcinoma, but is absent in lung cancer, prostate cancer, and non-mucinous ovarian cancer. It is often used in combination with antibodies to CK7 to distinguish different types of glandular tumour.<ref name=Leong>{{cite book|author=Leong, Anthony S-Y|author2=Cooper, Kumarason|author3=Leong, F Joel W-M|year=2003|title=Manual of Diagnostic Cytology|edition=2|publisher=Greenwich Medical Media, Ltd.|pages=171–172|isbn=1-84110-100-1}}</ref>

[[Image:Small intestine - ck20 - intermed mag.jpg|thumb|left|Micrograph showing CK20 immunostaining of normal small intestine.]]

[[File:CK7 and CK20 by body location.svg|thumb|center|400px|CK7 and CK20 expression by various body locations.<ref>Image by Mikael Häggström, MD. More info at image description page in Wikimedia Commons.</ref>]]

==References== {{reflist}}

==Further reading== {{refbegin | 2}} *{{cite journal |vauthors=Nordgírd O, Oltedal S, Kørner H, etal |title=The potential of cytokeratin 20 and mucin 2 mRNA as metastasis markers in regional lymph nodes of colon cancer patients investigated by quantitative RT-PCR. |journal=Int J Colorectal Dis |volume=24 |issue= 3 |pages= 261–8 |year= 2009 |pmid= 19119477 |doi= 10.1007/s00384-008-0613-y |s2cid=10831713 }} *{{cite journal |vauthors=Wong CS, Cheung MT, Ma BB, etal |title=Isolated tumor cells and circulating CK20 mRNA in pN0 colorectal cancer patients. |journal=Int. J. Surg. Pathol. |volume=16 |issue= 2 |pages= 119–26 |year= 2008 |pmid= 18387990 |doi= 10.1177/1066896907311901 |s2cid=29407811 }} *{{cite journal |vauthors=Nishigami T, Onodera M, Torii I, etal |title=Comparison between mucinous cystic neoplasm and intraductal papillary mucinous neoplasm of the branch duct type of the pancreas with respect to expression of CD10 and cytokeratin 20. |journal=Pancreas |volume=38 |issue= 5 |pages= 558–64 |year= 2009 |pmid= 19287335 |doi= 10.1097/MPA.0b013e31819f3bd6 |s2cid=30111257 }} *{{cite journal |vauthors=Saad RS, Silverman JF, Khalifa MA, Rowsell C |title=CDX2, cytokeratins 7 and 20 immunoreactivity in rectal adenocarcinoma. |journal=Appl. Immunohistochem. Mol. Morphol. |volume=17 |issue= 3 |pages= 196–201 |year= 2009 |pmid= 19098678 |doi= 10.1097/PAI.0b013e31819268f2 |s2cid=37115618 }} *{{cite journal |vauthors=Kim JJ, Lee HI, Park T, etal |title=Identification of 15 loci influencing height in a Korean population. |journal=J. Hum. Genet. |volume=55 |issue= 1 |pages= 27–31 |year= 2010 |pmid= 19893584 |doi= 10.1038/jhg.2009.116 |doi-access= free }} *{{cite journal |vauthors=González JJ, Bernardo CG, Sanz L, etal |title=Mismatch repair protein MSH2, cytokeratin 18 and cytokeratin 20 expression: clinicopathological correlation and prognostic value in colorectal cancer patients. |journal=Hepatogastroenterology |volume=54 |issue= 80 |pages= 2266–71 |year= 2007 |pmid= 18265645 }} *{{cite journal |vauthors=Wang YD, Wu P, Mao JD, etal |title=Relationship between vascular invasion and microvessel density and micrometastasis. |journal=World J. Gastroenterol. |volume=13 |issue= 46 |pages= 6269–73 |year= 2007 |pmid= 18069772 |pmc=4171242 |doi= 10.3748/wjg.13.6269 |doi-access=free }} *{{cite journal |vauthors=Chan CW, Wong NA, Liu Y, etal |title=Gastrointestinal differentiation marker Cytokeratin 20 is regulated by homeobox gene CDX1. |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=106 |issue= 6 |pages= 1936–41 |year= 2009 |pmid= 19188603 |doi= 10.1073/pnas.0812904106 |pmc=2644142|bibcode=2009PNAS..106.1936C |doi-access=free }} *{{cite journal |vauthors=Koga T, Tokunaga E, Sumiyoshi Y, etal |title=Detection of circulating gastric cancer cells in peripheral blood using real time quantitative RT-PCR. |journal=Hepatogastroenterology |volume=55 |issue= 84 |pages= 1131–5 |year= 2008|pmid= 18705345 }} *{{cite journal |vauthors=D'Armento G, Daniele L, Mariani S, etal |title=Added value of combined gene and protein expression of CK20 and CEA in non-macroscopically involved lymph nodes of colorectal cancer. |journal=Int. J. Surg. Pathol. |volume=17 |issue= 2 |pages= 93–8 |year= 2009 |pmid= 19074466 |doi= 10.1177/1066896908328574 |s2cid=3123711 }} *{{cite journal |vauthors=Eissa S, Zohny SF, Swellam M, etal |title=Comparison of CD44 and cytokeratin 20 mRNA in voided urine samples as diagnostic tools for bladder cancer. |journal=Clin. Biochem. |volume=41 |issue= 16–17 |pages= 1335–41 |year= 2008 |pmid= 18804101 |doi= 10.1016/j.clinbiochem.2008.08.085 }} *{{cite journal |vauthors=Lugli A, Tzankov A, Zlobec I, Terracciano LM |title=Differential diagnostic and functional role of the multi-marker phenotype CDX2/CK20/CK7 in colorectal cancer stratified by mismatch repair status. |journal=Mod. Pathol. |volume=21 |issue= 11 |pages= 1403–12 |year= 2008 |pmid= 18587323 |doi= 10.1038/modpathol.2008.117 |doi-access= free }} *{{cite journal |vauthors=He H, Fang W, Liu X, etal |title=Frequent expression of glypican-3 in Merkel cell carcinoma: an immunohistochemical study of 55 cases. |journal=Appl. Immunohistochem. Mol. Morphol. |volume=17 |issue= 1 |pages= 40–6 |year= 2009 |pmid= 18813128 |doi= 10.1097/PAI.0b013e31817b67d1 |s2cid=1735166 }} *{{cite journal |vauthors=Stenling R, Lindberg J, Rutegírd J, Palmqvist R |title=Altered expression of CK7 and CK20 in preneoplastic and neoplastic lesions in ulcerative colitis. |journal=APMIS |volume=115 |issue= 11 |pages= 1219–26 |year= 2007 |pmid= 18092953 |doi= 10.1111/j.1600-0643.2007.00664.x |s2cid=36381220 }} *{{cite journal |vauthors=Takano K, Kojima T, Ogasawara N, etal |title=Expression of tight junction proteins in epithelium including Ck20-positive M-like cells of human adenoids in vivo and in vitro. |journal=J. Mol. Histol. |volume=39 |issue= 3 |pages= 265–73 |year= 2008 |pmid= 18246436 |doi= 10.1007/s10735-008-9162-5 |s2cid=10932276 }} *{{cite journal |vauthors=Barbisan F, Santinelli A, Mazzucchelli R, etal |title=Strong immunohistochemical expression of fibroblast growth factor receptor 3, superficial staining pattern of cytokeratin 20, and low proliferative activity define those papillary urothelial neoplasms of low malignant potential that do not recur. |journal=Cancer |volume=112 |issue= 3 |pages= 636–44 |year= 2008 |pmid= 18072261 |doi= 10.1002/cncr.23212 |s2cid=22838425 |doi-access=free }} *{{cite journal |vauthors=Lagoudianakis EE, Kataki A, Manouras A, etal |title=Detection of epithelial cells by RT-PCR targeting CEA, CK20, and TEM-8 in colorectal carcinoma patients using OncoQuick density gradient centrifugation system. |journal=J. Surg. Res. |volume=155 |issue= 2 |pages= 183–90 |year= 2009 |pmid= 19645077 |doi= 10.1016/j.jss.2007.10.013}} *{{cite journal |vauthors=Ishida M, Kushima R, Okabe H |title=Aberrant expression of class III beta-tubulin in basal cell carcinoma of the skin. |journal=Oncol. Rep. |volume=22 |issue= 4 |pages= 733–7 |year= 2009 |pmid= 19724850 |doi= 10.3892/or_00000494|doi-access=free }} *{{cite journal |vauthors=Qiao JL, Meng XK, Zhang JJ, etal |title=[Expression of CK20 mRNA in the peripheral blood around postoperative chemotherapy in patients with gastric cancer and its clinical significance] |journal=Zhonghua Wei Chang Wai Ke Za Zhi |volume=12 |issue= 1 |pages= 32–5 |year= 2009 |pmid= 19145500 }} {{refend}}

Category:Keratins