Chung et al. (2009) found that Rab3b is more highly expressed in A10 vs. A9 dopaminergic neurons, which could be one reason accountable for the relatively greater vulnerability of A9 neurons compared with A10 neurons; overexpression of Rab3b in A9 neurons in rats confers a protective effect and leads to improved motor functions in a PD model. The gene discussed is RAB3B; the disease is Parkinson disease.