PTGS2 and gastric cancer: Potentially, this may reflect the carcinogenic drive of the transgenes Ptgs2 (encoding COX2), Ptges (encoding microsomal prostaglandin E synthase 1), and Wnt1 in whole gastric epithelia of Gan mice, which leads to 100 % tumor incidence and more aggressive cancers than the sporadic gastric cancers observed in humans [12].