Figure 6.

Role of the MAPK signaling pathways in PM_2.5-mediated autophagy. Representative images are shown in the left panels, and quantification relative to β-actin expression (mean ± SD of at least 3 separate experiments) is shown in the right panels. A, C, E. PM_2.5 activates MAPKs in A549 cells. Cells were treated with 100 μg/ml PM_2.5 for variable periods (0, 6, 12 and 24 h). ERK, p-ERK, p38, p-p38, JNK and p-JNK expression was assessed by western blot analysis. B, D, F. Blocking ERK and p38 MAPKs enhances PM_2.5-mediated autophagy. Cells were treated with 100 μg/ml PM_2.5 for 24 h following 6 h pretreatment with ERK inhibitor U1026 (5 μM), p38 inhibitor SB203580 (10 μM), or JNK inhibitor SP6005 (50 μM). MAPKs and LC3 expression was assessed by western blot analysis.