Moreover, an activation of the PERK branch of the UPR was observed that was induced by defective mitochondria, and PERK inhibition is neuroprotective in parkin mutant flies (Celardo et al., 2016), as well as in flies harboring mutants of pink1, a gene in which mutations in humans are associated with both genetic and sporadic PD (Valente et al., 2004a, b). Here, PRKN is linked to Parkinson disease.