AST IV (100 µM) and SB203580 ameliorate apoptosis in PC12 cells induced by amyloid β25-35 via p38 MAPK. (A) SOD activity and (B) MDA content were measured from the supernatants from the control, model, AST IV and SB203580 groups. (C) FACS was performed to assess intercellular ROS levels in the control, model, AST IV and SB203580 groups. (D) Western blot analyses of p38 MAPK and p-p38 MAPK. (E and F) Reverse transcription semi-quantitative polymerase chain reaction and western blot analyses of BIP/GRP78, GADD153/CHOP and caspase-3 were performed of the control, model, AST IV and SB203580 groups. **P<0.01 vs. Control; #P<0.05, ##P<0.01 vs. Model. AST IV, astragaloside IV; BIP/GRP78, binding immunoglobulin protein/glucose-regulated protein 78; GADD153/CHOP, growth arrest- and DNA damage-inducible gene 153/C/EBP homologous protein; MAPK, mitogen-activated protein kinase; MDA, malondialdehyde; SOD, superoxide dismutase.