The manuscript entitled “Physiological GDNF plays no role in dopamine neuron protection and restoration in a proteasome inhibition model of Parkinson’s disease” reports that they fail to find any neuroprotective or neurorestorative effects of a GDNF hypermorphic allele that increases endogenous GDNF expression by 2-3 fold in an LC model of PD in adult mice. The gene discussed is GDNF; the disease is Parkinson disease.