MPP+ induces a dose- and time-dependent increase in intracellular ROS in the N27 dopaminergic cells. (A) N27 cells were treated with increasing concentrations of MPP+ (up to 1000 μM) for 18 hours and H2O2 (ROS) levels were measured using carboxy-H2-DCFDA fluorescence and flow cytometry. ROS levels are reported as fold increase above values observed in cells that received no MPP+, control. * p < 0.01 compared to 0 μM MPP+ control. (B) N27 cells were treated with 300 μM MPP+ and ROS levels were detected at different times after treatment. # represents p < 0.05 compared to 0 hour and * represents p < 0.01 compared to 0 hour. Data are from 3 independent experiments with n = 6 wells per experiment.