Figure 4.

ER stress-CHOP apoptotic signal is involved in PM2.5-triggered apoptosis. (A) HaCaT cells were pretreated with 4-PBA (3 mM) for 2 h and then treated with PM2.5 for 24 h. Western blot was used to detect the expression levels of GRP78 and CHOP. (B) Statistics of GRP78 protein alteration. (C) Statistics of CHOP protein alteration. The gray levels were analyzed by the Image J software. (D) Apoptosis was analyzed with Annexin V-FITC and PI staining, and observed under a fluorescent microscope. Scale bar = 50 μm. Values are mean ± SD. **p < 0. 01, ***p < 0.001 versus the control group; ## p < 0.01 versus the PM2.5 treatment alone group.