To investigate the effect of LAR heterozygous knockout on astrocytic GDNF production and its neuroprotective capability in this rotenone-induced PD model system, the cocultures of wild-type (WT) U251 or LAR heterozygous knockout U251 cells with SH-SY5Y cells were treated with or without rotenone. The gene discussed is PTPRF; the disease is Parkinson disease.