PRKN and Parkinson disease: In the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of PD, the expression levels of FIS1 are elevated concomitantly with the reduced levels of MFN2 and Nrf2 [86], although Mendes et al. [87] have reported that MPTP transiently increases the expression of Nrf2 and parkin.