The use of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to generate rodent and non-human primate PD models (Langston et al., 1984; Johannessen et al., 1985; Jenner and Marsden, 1986; Snyder and D’Amato, 1986; Williams, 1986; Tipton and Singer, 1993; Schulz et al., 1995; Przedborski et al., 1996; Ara et al., 1998) gives a clue: affected cells must have the DAT dopamine transporter, i.e., unlike neurons unable to uptake MPTP, dopaminergic neurons are the most affected. The gene discussed is SLC6A3; the disease is Parkinson disease.