Infection of mouse epithelial cells with H. pylori activates the p38 stress pathway. Lysates from AGS and GSM06 cells infected with 26695, 26695 CagA, HpM5 or HpM5 CagA for either 5, 30, 60 or 120 minutes were resolved by SDS-PAGE and analyzed by immunoblot using total and phospho-p38 specific monoclonal antibodies. Data were evaluated as the ratio of phospho-p38 to total p38. Significant changes in phosphorylation were determined as compared to control, unstimulated cells. *P < 0.05.