The regulation of TH activity by phosphorylation has been studied in various PD models in vivo, e.g., using neurotoxic models with the administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) [24,25,26] and 6-hydroxydopamine (6-OHDA) [27]. The gene discussed is TH; the disease is Parkinson disease.