FigureĀ 3.
Cytokeratin 20 (CK20) is a protein that in humans is encoded by the KRT20 gene. CK20 is a type I cytokeratin. It is a major cellular protein of mature enterocytes and goblet cells and is specifically found in the gastric and intestinal mucosa. It is used as a marker for colorectal adenocarcinoma and can be seen here with the positive brown staining of the cytoplasm.