Immunohistochemistry for Cytokeratin 5/6 (CK5/6) aims to detect these high molecular weight keratins. They are normally expressed in the basal and parabasal layers of stratified squamous epithelium, as well as in transitional epithelium and myoepithelial cells of breast glands. It is a characteristic marker for Squamous Cell Carcinoma (SCC) and aids in distinguishing it from Adenocarcinoma.