S100A8 and gastric adenocarcinoma: To first examine whether the middle fragment of CagA (CagA-M, aa 257–880) alone is capable of interacting with gastric epithelial cells, we incubated the human gastric adenocarcinoma cell line AGS with purified CagA-M (1 mg/mL) for 24 h and examined cell morphology using phase-contrast microscopy.