Cytokeratin 19 (Biotin)

Reacts with the smallest human cytokeratin (Mr 40kD). No crossreactivity with other cytokeratins. Reacts strongly with luminal (secretory) epithelial cells but does not stain the basal (myoepithelial) cells. There is a subset ofsecretory epithelial cells which were Keratin 19 and are thought to be precursors to keratin 19+ cells.