S100A8 and gastric carcinoma: The pathogenesis of CagA was induced by which was injected into epithelial cells by the type IV secretion system of H. pylori. To mimic injected CagA in the host cell, we first used the standard calcium phosphate precipitation method to establish stable CagA-expressing gastric carcinoma AGS cells to explore whether CagA protein affects miRNA expression (Figure 1a and 1b).