We examined the cell proliferative, neurogenic, and behavioral effects of transforming growth factor α (TGFα) in a 6-OHDA Parkinson9s disease model when compared with naive rats. Intrastriatal TGFα infusion induced significant proliferation, hyperplastic nodules, and substantial migratory waves of nestin-positive progenitor cells from the adult subventricular zone (SVZ) of dopamine-denervated rats. Interestingly, SVZ cells in naive rats displayed proliferation but minimal migration in response to the TGFα infusion. The cells in the expanded SVZ accumulated cytoplasmic β-catenin, indicating activation of classical Wnt signaling. However, no evidence of any neuronal differentiation was found of these recruited progenitor cells anywhere examined in the brain. Consequently, no evidence of dopaminergic (DA) neurogenesis was found in the striatum or substantia nigra in any experimental group, and amphetamine-induced behavioral rotations did not improve. In summary, the cells in the TGFα-induced migratory cellular wave remain undifferentiated and do not differentiate into midbrain-like DA neurons.