K-rasLA1/+; Msh2−/− mice showed similar pathology to K-rasLA1/+ mice 1, from mild hyperplasia, progressing to adenoma and adenocarcinoma, with the exception of invasive adenocarcinomas present at 100 days in the K-rasLA1/+; Msh2−/− mice (Fig. 3), a feature not commonly seen in K-rasLA1/+ until the latter were closer to 180 days of age (data not shown). This evidence concerns the gene MSH2 and adenocarcinoma.