PRKN and Spinocerebellar ataxia type 3: Moreover, no changes in MFN2 protein levels (a substrate of Parkin) have been observed in MJD135 mice or PC6-3 Q108 cells, thus further supporting the view that, in patients with SCA3/MJD, mitophagy is not induced by the activation of the Parkin/PINK1 pathway [22].