FIS1 and Parkinson disease: Zhang et al. reported increased FIS1 protein levels in mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; a precursor of the mitochondrial complex I inhibitor 1-methyl-4-phenylpyridinium (MPP+), a mouse model of PD, while overexpression of DJ-1 (a protein mutated in familiar PD) repressed FIS1 upregulation via RING-finger protein-5-mediated FIS1 ubiquitination and degradation [116].