PTGS2 and neoplasm: Moreover, though the high level of prostaglandin E2 (PGE2), induced by the overexpressed COX-2, can cause the proliferation of tumor cells, stimulate Bcl-2 protein expression that inhibits apoptosis, and promote the malignant biological behavior of tumors [83], several studies have revealed that COX-2 inhibitors may exert anticarcinogenic effects, not only through COX-2-dependent but also COX-2-independent mechanisms.