Dose-dependent effect of the combination treatment of 1.56 μM BSO and 6-OHDA on the cell viability of PC12 cells. PC12 cells were pretreated for 6 or 24 h with BSO followed by the treatment of different concentrations of 6-OHDA for 24 h on the cell viability of PC12 cells (a, b). The values shown are the mean ± SD of at least three independent experiments performed with 6–8 replicates. One-way ANOVA analysis followed by Tukey’s multiple comparison post hoc test was performed (***p \ 0.0001, **p \ 0.001, #p \ 0.05 compared to control and ***p \ 0.0001, **p \ 0.001, *p \ 0.01, #p \ 0.05 compared to BSO group)