MFN2 and Parkinson disease: Alterations in Mfns either directly, in Mfn2 ablated MEFs, or as a consequence of dysfunctional mitophagy, in PD mutant flies, are known to induce the ISR, a protective pathway that leads to a reduction in global protein synthesis rates upon detection of cellular stress (Munoz et al, 2013; Celardo et al, 2016).