gba+/+ and gba−/− neurons were incubated with oligomycin—an ATPase inhibitor —in order to assess the function of the MRC, demonstrating that the ΔΨm in gba+/+ neurons was not affected by incubation with oligomycin, but was significantly reduced in gba−/− neurons, suggesting that the reduced ΔΨm is maintained by ATP synthase (complex V) working in reverse, which is a mechanism implicated in PINK1 KO-associated PD. The gene discussed is GBA1; the disease is Parkinson disease.