CXCL8 and gastric cancer: In particular, DU-promoting gene cluster (dupA cluster) and virB gene forming a type IV secretory system (T4SS) have been proposed as a risk marker for both DU disease and the production of the pro-inflammatory IL-8 cytokine [22], while the intact H. pylori cag-PAI region has been associated with both DU and GC [23, 24].