a PC12 cells were treated with different concentrations of MPP+ for 48 h and then the cell viability was measured using alamarBlue assay. Data were quantified as mean ± SEM from three independent experiments. ***P < 0.001 vs. Ctrl group. b PC12 cells were pretreated with different concentrations of CB6 for 30 min, followed by cotreatment with MPP+ (1 mM) for another 48 h. Data were quantified as mean ± SEM from three independent experiments. **P < 0.01 and ***P < 0.001 vs. MPP+ group. c After treatment of CB6 (20 µM) and CQ (50 µM) for 30 min, PC12 cells were treated with MPP+ (1 mM) for another 48 h. Data were quantified as mean ± SEM from three independent experiments. ***P < 0.001 vs. MPP+ + CB6 group. After treatment of CB6 (20 µM) and SAR405 (5 µM) (d) or Spautin1 (10 µM) (e) for 30 min, PC12 cells were treated with MPP+ (1 mM) for another 48 h. Data were quantified as mean ± SEM from three independent experiments. *P < 0.05, **P < 0.01 and ***P < 0.001 vs. MPP+ + CB6 group. (f) PC12 cells were transfected with nontarget or Becn1 specific siRNA for 24 h, followed by co-treatment with CB6 (20 µM) and MPP+ (1 mM) for another 48 h. Data were quantified as mean ± SEM from three independent experiments. **P < 0.01 vs. siNT + MPP+ group. n.s., not significant. Western blots show the knockdown efficacy of Becn1 in PC12 cells.