In addition, Nod2−/− mice showed significantly less cleaved caspase-3 positive epithelial cells in the intestinal villi (P<0.01; Fig. 4b) and crypts (P<0.001; Fig. 4b) surrounding PPs, suggesting that cell death induced by Yersinia infection was at least in part related with apoptosis. This evidence concerns the gene CASP3 and Yersinia infectious disease.