Effects of endogenous or exogenous HSP70 on apoptosis in AGS cells with H. pylori infection. (A) Representative TUNEL staining of AGS cells transfected with HSP70 siRNA or control vector following incubation with H. pylori for 48 hours. An increase in the number of TUNEL-positive cells (brown-stained nuclei, black arrows) was evident in HSP70 siRNA transfected cells. (B) Immunoblotting analyses were performed to determine the target pro-apoptotic proteins expression in HSP70 siRNA transfected AGS cells with H. pylori infection.(C)&(D) Excellular HSP70 (50 ng/ml) incorporated into the incubation medium of HSP70 siRNA transfected AGS cells and H. pylori (1:200) for 48 h. The function of exogenous HSP70 on the target pro-apoptotic proteins, as well as p21 and PCNA were confirmed by immunoblotting. β-actin was used as an internal control.