Cytokeratin 4 (KRT4) is an intermediate filament protein associated with Cytokeratin 13 (KRT13) . It is expressed in suprabasal cells of non-keratinized stratified squamous epithelium of esophagus, cornea, anus, larynx, pharynx and tongue. Decreased expression of KRT4 is associated with head and neck squamous carcinoma. It is helpful in differentiation of squamous cell carcinoma of esophagus origin from that of thyroid origin. Primary antibodies are available purified, or with a selection of fluorescent CF® Dyes and other labels. CF® Dyes offer exceptional brightness and photostability. Note: Conjugates of blue fluorescent dyes like CF®405S and CF®405M are not recommended for detecting low abundance targets, because blue dyes have lower fluorescence and can give higher non-specific background than other dye colors.