Examples of CD133 immunohistochemical staining in human colon samples. (A and B) Normal colonic mucosa. Note the rare (→) positivity for CD133 (A, × 200 and B, × 400). (C) A early dysplastic lesion of colon tumorigenesis showing a marked positive immunostaining for CD133 (× 200). (D) Example of a moderately differentiated NAS adenocarcinoma displaying a diffuse staining for CD133 (× 200). (E and F) Examples of mucinous poorly differentiated adenocarcinomas displaying a strong and diffuse cytoplasmic staining for CD133 with a clear immuno-negativity of nuclei (× 200 and × 550).