Figure 2. Disturbance of autophagy rendered mouse alveolar epithelial cells vulnerable to apoptosis after tunicamycin-induced ER stress. Mouse alveolar epithelial MLE12 cells were treated with vehicle control or 0.5 and 1 μg/ml tunicamycin alone or in combination with chloroquine 10µM for 24h. Apoptosis was determined by flow cytometric analysis of Annexin-V–FITC/ PI-stained cells after 24 h. Representative data (A) and cumulative data (B) from 3 independent experiments. (C) Representative immunoblot of pro- and active CAS3 in mouse alveolar epithelial MLE12 cells treated as indicated. β-tubulin was used as loading control. Densitometry. Protein levels were normalized to vehicle control. Results represent mean ± SD. Statistical significance was determined by one-way ANOVA (* p< 0.05).