Caspases 3, 8 and 9 activity in rat alveolar type II cells with or without exposure to smoke and mechanical ventilation. Smoke exposure and mechanical ventilation alone did not lead to an increase. The combination of the two stimuli resulted in nonsignificant increases in caspase activity compared to all other groups. ATII: Alveolar type II cells; NS-NV: nonsmoke/nonventilated; NS-V: nonsmoke/ventilated; S-NV: smoke/nonventilated; S-V: smoke/ventilated. Bars represent mean and standard deviation of the data.