The MNU mouse model of gastric cancer has been extensively used for investigating the role of various signaling pathways or transcription factors in gastric carcinogenesis, including the roles of p53 [50], NF-κB [51], MAPK pathway [52,53], Cox-2 [54,55], β-catenin [54], E-cadherin [56], and KLF4 [57]. This evidence concerns the gene PTGS2 and gastric cancer.