S100A8 and infection: To measure CagA expression in a cell culture infection model, the gastric adenocarcinoma cell line AGS was infected with strains PMSS1, SF-1, SL-2, MF-3, ML-1, and ΔcagAFL-2, and the levels of total and phosphorylated CagA were measured by Western blotting (Fig. 3C).