To improve our understanding of the molecular mechanisms underlying PD pathogenesis and progression, we have started our experiments on SH-SY5Y neuroblastoma cells because of their human origin and because these cells express tyrosine hydroxylase (TH), dopamine-beta-hydroxylase, and the dopamine transporter, thus recapitulating many characteristics of human dopaminergic neurons. The gene discussed is SLC6A3; the disease is Parkinson disease.