Keratin 5 &14

Cytokeratins (CK) are intermediate filaments of epithelial cells, both in keratinizing tissue (ie., skin) and non-keratinizing cells (ie., mesothelial cells). Although not a traditional marker for endothelial cells, cytokeratins have also been found in some microvascular endothelial cells. Atleast 20 different cytokeratins (CK) in the molecular range of 40-70 kDa and isoelectric points of 5-8.5 can be identified using two dimensional gel electrophoresis. Biochemically, most members of the CK family fall into one of two classes, type I (acidic polypeptides) and type II (basic polypeptides). At least one member of the acidic family and one member of the basic family is expressed in all epithelial cells. Monoclonal antibodies to cytokeratin proteins can be useful markers for tumor identification and classification.Belonging to the type A (acidic) subfamily of low molecular weight keratins and existing in combination with keratin 5, keratin 14 distinguishes stratified epithelial cells from simple epithelial cells and is useful in identification of squamous cell carcinomas. It is considered a prognostic marker in breast carcinomas.