Measurement of apoptosis in PC12 cells against 6-OHDA toxicity upon caspase inhibition using pan-caspase inhibitor, Z-VAD-FMK. PC12 cells were pretreated with 100 μM of Z-VAD-FMK for h followed by co-treatment with varying concentrations of 6-OHDA (100, 75, 50, and 25 μM) for 24 h. 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 \ 0.001, #p \ 0.05 compared to control group)