Immunohistochemistry was performed to examine COX-2 protein expression in the samples.The results showed that normal samples did not express COX-2, while samples withpre-neoplastic lesions (chronic gastritis, atrophic gastritis and metaplasia) or tumorswere positive for COX-2 expression (Figures 3 and4). This evidence concerns the gene PTGS2 and chronic atrophic gastritis.