TH and Parkinson disease: It remains unclear if the various subtypes of TH-positive GABAergic cells described in TH-Cre mice (Tepper et al., 2010) represent the same neuronal phenotype as those seen in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated monkeys and Parkinson’s disease (PD) patients.