Figure 2. PERK activation with SB202190 is induced by ROS production. (A–C) SH-SY5Y cells were treated with 20 μM SB202190 for 3 h in the presence or absence of MitoTEMPO (100 nM, 1 h). (A) Cells were stained with MitoSOX (red), and then the nuclei were stained with DAPI (blue). Images were acquired by confocal microscopy. Scale bar, 10 μm. (B) mtROS was measured by flow cytometry. Fold changes in MitoSOX intensity are indicated at right. Data are mean ± SD (n=3); ***p<0.001. (C) Western blotting was performed to detect the phosphorylation of PERK, eIF2α, and ATF4.