Figure 2: RC defect-augmented loss in cell viability during H2O2 stress as measured by the MTT assay. (a, b) Dose-dependent cytotoxic effect induced by H2O2 exposure in control (filled columns) and ρ 0 RBA1 astrocytes (empty columns); (a) time point for H2O2 exposure: 10 min and (b) 30 min. There were no statistically significant differences between the two groups in the cell viability at different concentration for 10 minutes ( ) (a). 20 mM H2O2 caused a statistically significant loss in cell viability in ρ 0 astrocytes for 30 min when compared to control cells ( ) (b). Data were expressed as mean values ± SE of four separate experiments. .