Activation of non-canonical NF-κB, as detected by p52 nuclear staining, was observed in H. pylori-infected tissue and gastric cancers, correlating with CEACAM1 expression in 46% of patient samples with H. pylori-induced gastritis, 62.5% of intestinal-type gastric tumor samples and in 100% of diffuse-type gastric cancer samples analysed. The gene discussed is NFKB1; the disease is gastric cancer.