Our Co-IP and ChIP assays showed the interaction between JMJD2B and NF-κB in gastric cancer cells and the increased binding of JMJD2B with NF-κB to COX-2 promoter coupled with the decrease of H3K9me3 and increase of H3K9me2 by H. pylori infection. This evidence concerns the gene NFKB1 and gastric cancer.