Cigarette smoke extract induced necrosis with no or little evidence of apoptosis in human adenocarcinoma cells (A549). Human adenocarcinoma cells (A549) were treated with media alone (control) and various concentrations of CSE; a) control, b) CSE (1.0%), c) CSE (2.5%), d) CSE (5.0%), e) CSE (7.5%), f) CSE (10%) for 24 hr. Results are mean of 3 experiments ± SEM. #p < 0.01, and §p < 0.001 compared with control group. L = Live; A = Apoptosis; N = Necrosis.