This MAb reacts with a wide variety of simple epithelia. It does not react with stratified squamous epithelia. It reacts with epithelial tumors of the gastrointestinal tract, lung, breast, pancreas, ovary, and thyroid. Cytokeratin 18, which belongs to the type A (acidic) subfamily of low molecular weight keratins, exists in combination with cytokeratin 8. It is reported that tissues from gastrointestinal tract are positive for both cytokeratin 8 and 18 but do not contain cytokeratin 14. Tissues from gastrointestinal tract, respiratory tract and urogenital tract, as well as endocrine and exocrine tissues and mesothelial cells are positive for cytokeratin 18. 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.