Keratin 20

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RefSeq (mRNA)



RefSeq (protein)



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Keratin 20, often abbreviated CK20, is a protein that in humans is encoded by the KRT20 gene.[1][2][3]

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.[4]

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.[5]

File:Small intestine - ck20 - intermed mag.jpg
Micrograph showing CK20 immunostaining of normal small intestine.


  1. Moll R, Zimbelmann R, Goldschmidt MD, Keith M, Laufer J, Kasper M, Koch PJ, Franke WW (June 1993). "The human gene encoding cytokeratin 20 and its expression during fetal development and in gastrointestinal carcinomas". Differentiation. 53 (2): 75–93. doi:10.1111/j.1432-0436.1993.tb00648.x. PMID 8359595.
  2. Ye X, Li Y, Hou G, Liu Z, Chen T (May 2002). "[Significance of cytokeratin gene (CK-20 mRNA) expression in metastatic lymph nodes in colon carcinoma patients]". Zhonghua Zhong Liu Za Zhi (in Chinese). 24 (3): 261–3. PMID 12515621.
  3. Schweizer J, Bowden PE, Coulombe PA, Langbein L, Lane EB, Magin TM, Maltais L, Omary MB, Parry DA, Rogers MA, Wright MW (July 2006). "New consensus nomenclature for mammalian keratins". J. Cell Biol. 174 (2): 169–74. doi:10.1083/jcb.200603161. PMC 2064177. PMID 16831889.
  4. Moll R, Schiller DL, Franke WW (August 1990). "Identification of protein IT of the intestinal cytoskeleton as a novel type I cytokeratin with unusual properties and expression patterns". J. Cell Biol. 111 (2): 567–80. doi:10.1083/jcb.111.2.567. PMC 2116178. PMID 1696264.
  5. Leong, Anthony S-Y; Cooper, Kumarason; Leong, F Joel W-M (2003). Manual of Diagnostic Cytology (2 ed.). Greenwich Medical Media, Ltd. pp. 171–172. ISBN 1-84110-100-1.

Further reading

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