Figure 1. Cyclooxygenase-2 expression in pterygium tissue. A: Hematoxylin and eosin staining of human pterygium (case 10) is demonstrated. B: Immunohistochemistry of human pterygium using anti-cyclooxygenase-2(COX-2) antibody was performed. Diffuse expression (grade 2) of COX-2 is seen in the epithelial layer with some strong COX-2-expressing cells in both the epithelium and stroma. Endothelial cells lining vessels were also strongly positive for COX-2 expression in this sample. The arrow indicates the magnified area. C, D: COX-2 expression was not found in the epithelial or stromal layer in the normal control. E: Strong COX-2 expression in colon cancer was demonstrated as the positive control. F: western blot analysis revealed various degrees of COX-2 expression in pterygium tissue (cases 2, 3, 4, 6, and 10); however, no COX-2 band was observed in the control tissue.