GPR37 and Parkinson disease: The homozygous Gpr37<tm2Gtva> animals also presented with a striking resistance to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a potent PD-inducing neurotoxin, which causes the specific degeneration of mammalian substantia nigra dopaminergic neurons [11].