PARK7 and Parkinson disease: Dysfunction of the ETC, compromised ΔΨm, and superoxide and ROS by-products of OXPHOS are strongly connected with the generation of mitochondrial oxidant stress in both DJ-1 knockout animals [25] and iPSC-derived dopaminergic neurons from PD patients with a loss-of-protein mutation in DJ-1 [34], as was demonstrated using a redox-sensitive variant of green fluorescent protein (roGFP) with a mitochondrial matrix targeting sequence.