To clarify the initiating role in gastric carcinogenesis as well as the histologic characterization of tumor in Fbxw7 allele haploinsufficient mice, we generated Fbxw7 heterozygous knockout mice (Fbxw7+/−) and treated them with chemical carcinogen N-methyl-N-nitrosourea (MNU) at 5–6 weeks of age. Here, FBXW7 is linked to neoplasm.