In D. melanogaster, the overexpression of familial PD-mutated Parkin or PINK1 has been shown to activate the PERK branch of the UPRER and to induce an increase in connectivity between the ER and mitochondria in a mitofusin-dependent manner [105], as well as in a Miro- and mitochondrial Ca2+ shuttling-dependent manner [75]. The gene discussed is PRKN; the disease is Parkinson disease.