POLG and Parkinson disease: Nevertheless, because cell culture studies in vitro provide a compelling case for Parkin activation in stress-evoked mitochondrial quality control pathways [4–6], it will be vital to investigate if nigrostriatal mitophagy is specifically affected in models of constitutive mitotoxicity reporting PD-relevant pathology, e.g. Polγ mutator mouse crossed with Parkin knockout mice [21,62].