Figure 4.

Activation of MAPKs by blue light and H₂O₂. (A,B) Western blot analysis and (C,D) its quantification of P-JNK, P-p38 and P-ERK levels in PAC-2 cells exposed either to blue light (B,D) or treated with 300 μM H₂O₂ (A,C) for 0, 5, 15, 30, 60, 120, 180 min. (E–G) P-JNK and P-p38 expression in PAC-2 cells pre-treated for two hours with (E) vehicle (control) (F) 20 μM VAS 2870, or (G) 6 mM NAC before blue light exposure. (H,I) Quantification of the western blotting data presented in (E–G). (C,D,H,I) Means of fold induction relative to time 0 ± SD are plotted on the y-axis and times are plotted on the x-axis. Levels of α-vinculin were used as a loading control. Quantification was performed with Image J software. Statistical analysis of the differences between time 0 and the peaks of expression is represented by asterisks (*) where *p < 0.05; **p < 0,01; ***p < 0,001. Each western blotting panel is assembled from cropped western blotting images (see Supplementary material file for the original images). In the case of the results for P-p38 in panel F, the 15 minutes sample has been digitally shifted to occupy the correct position in the chronology of the timecourse (as indicated in the original western blot image presented in the Supplementary material file).