Figure 3

Mn²⁺ cytotoxicity is associated with JNK activation.

(a) Representative western blot showing time-dependent JNK phosphorylation upon treatment with 1 mM of Mn²⁺ in both S-DMT1 and vector cells. S-DMT1 cells displayed more robust JNK phosphorylation compared to vector cells. 1 mM Fe²⁺ treatment of both cell lines did not increase JNK phosphorylation. (b) S-DMT1 cells treated with 1 mM of Mn²⁺ for 12 h increased (*p < 0.05) JNK phosphorylation compared to untreated. This JNK phosphorylation induced by Mn²⁺ was significantly (^p < 0.05) reduced with SP600125 (25 μM) treatment. Bar chart shows fold change of phosphorylated JNK protein levels over untreated (n = 3, Student’s t-test), with error bars representing standard error of mean (S.E.M.). Corresponding full-length blots are presented in Supplementary Fig. 1. (c) MTT cell viability assay showing the protective effect of SP600125 against Mn²⁺-mediated cytotoxicity (*p < 0.05, ***p < 0.001, n = 3, two-way ANOVA, Bonferroni post hoc test). Phase contrast images show the reduced vulnerability of S-DMT1 cells to 0.5 mM Mn²⁺ cytotoxicity when treated with SP600125 for 24 h.