The results showed that the expression of COX-1 increased after Lactobacillus stimulated NCI-N87 cells, while the expression of COX-1, COX-2 and COX-1-IR did not change significantly after Bifidobacterium stimulated AGS and NCI-N87 cells, suggesting that Lactobacillus can inhibit the growth of metastatic GC cells by inducing the production of cytoprotective COX-1. This evidence concerns the gene PTGS1 and gastric cancer.