ihcDirect® CK5 antibody recognizes human cytokeratin 5, an intermediate filament protein of 58 kD molecular weight within the cytokeratin family. CK5 is expressed in squamous cell epithelium, myoepithelial cells of the breast, mesothelium and the basal cells of the prostate. The key component in this kit is horseradish peroxidase (HRP) polymer (pHRP) labeled rabbit anti-human cytokeratin 5 monoclonal antibody (clone R226). The ihc Blocker provided in the kit used prior to applying pHRP-Cytokeratin 5 conjugate will reduce background and nonspecific staining. Chromogen 3,3’diaminobenzidine (DAB) is used in this kit.