Besides, COX-2 inhibits the anti-tumor immune response by up-regulating cell invasion.17 The positive expression rates of COX-2 herein were 3.3%, 21.7% and 55.0% respectively in normal, neoplastic and cancer groups, indicating that COX-2 expression increased during the pathological changes of the endometrium. The gene discussed is PTGS2; the disease is cancer.