On the other hand, although an increase in BrdU and NeuN co-labeling was seen in the SN of a 6-OHDA PD rat model, none of the newly generated neurons developed into DARPP-32-positive dopaminergic neurons, arguing against the complete differentiation/maturation and functional integration of these newly generated neurons into the nigrostriatal circuitry (Mohapel et al., 2005). The gene discussed is PPP1R1B; the disease is Parkinson disease.