CEACAM5 and infection: In the infection study, we detected a larger amount of CagA proteins in lysates prepared from YTN2-derived cells stably expressing CEACAM1 (YTN2/hCEACAM1) or CEACAM5 (YTN2/hCEACAM5), possibly due to increased binding of H. pylori to the surface of mouse gastric epithelial cells expressing these human CEACAM proteins (Figure 4A, Supplementary Figures S3 and S4), providing additional evidence that both human CEACAM1 and human CEACAM5 efficiently bind to H. pylori HopQ.