The MN9D cell line, a fusion product of mesencephalic dopaminergic neurons and N18TG neuroblastoma, was previously demonstrated to synthesize, release, and take up dopamine.35, 36 As determined by immunocytochemistry, exposure of MN9D dopaminergic cells to 50 μM MPP+ for 36 h or longer caused a significant reduction in cdr2 levels, whereas numbers of cells in culture remained the same regardless of drug treatment (Figure 4b). The gene discussed is CDR2; the disease is neuroblastoma.