In order to better understand a regulatory function of CIB1 in the pathogenesis of Parkinson’s disease, we have now investigated the inhibitory action of CIB1 against dopaminergic neurotoxicity in a mouse model of the disease using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The gene discussed is CIB1; the disease is Parkinson disease.