To elucidate the impact of COX-1, COX-2, and mPGES-1 expression on tumor burden, we implanted ptgs1-KO, ptgs2-KO, ptges-KO, or scramble cells into the flank of syngeneic immunocompetent C57BL/6J mice and compared the tumor growth. The gene discussed is PTGS2; the disease is neoplasm.