Amphiregulin expression in normal colonic mucosa. 6a. Positive staining (brown) for amphiregulin is seen in this section through a normal colonic mucosal gland. Staining is much stronger in the surface epithelial cells (solid arrow head) than in the crypt epithelial cells (open arrow head). Relationship between amphiregulin and COX-2 expression in human colorectal cancer. 6b. Representative paired images of immunocytochemistry for COX-2 (left) and amphiregulin (right) in a selection of tumour samples demonstrating a concordance in the localisation of positive staining within individual tumour specimens. Nuclear localisation of amphiregulin expression in colorectal tumour. Figure 6c (Bottom left panel) Focal areas of positive amphiregulin staining were observed in the nuclei of tumour cells (representative image with arrow head indicating positive nuclear staining).