(A) Cell death rate (%) after osmotic (left panel) or heat (right panel) shock for various periods as indicated. (B) Caspase-3 activity in cells treated with 0.1 mol/L NaCl (lanes 1 to 7) or incubated at 42°C (lanes 8 to 14) for the periods indicated. Lanes 7 and 14: activity in the cells treated with NaCl (lane 7) or heat (lane 14) for 1 hour followed by incubation for an additional 24 hours under normal conditions. (C) DNA fragmentation of the cells treated with 0.1 mol/L NaCl (left panel) or 42°C (right panel) for various periods as indicated. Lanes 1 and 7: molecular weight marker. Lanes 6 and 12: cells treated with the stresses for 1 hour followed by a further 24-hour incubation under normal conditions.