In a 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced PD mouse model, EGCG (25 mg/kg/day) was shown to inhibit the loss of tyrosine hydroxylase (TH)-positive cells in the substantia nigra (SN) and to prevent the reduction in TH activity in the striatum. The gene discussed is TH; the disease is Parkinson disease.