【Abstract】 AIM: To investigate the effect of proteasome inhibitor MG132 on the proliferation and apoptosis of dopaminergic PC12 cells. METHODS: PC12 cells were treated with MG132 at different concentrations for 3 d. The effect of MG132 on the proliferation of PC12 cells was analyzed through MTT assay and the effect of MG132 on the apoptosis of PC12 cells was analyzed through Giemsa staining and flow cytometry. RESULTS: Treated for a same period (3 d), the inhibitory effect of MG132 on PC12 cell proliferation enhanced with the increment of the concentration of MG132(0, 1, 2.5, 5, 10, 20 μmol/L). The inhibitory rate exceeded 40% when the MG132 concentration was 2.5 μmol/L, and the 50% inhibiting concentration (IC50)was 3.78 μmol/L. MG132 also induced the apoptosis of PC12 cells obviously. The apoptosis index of the cells treated by MG132 at 2.5 μmol/L for 3 d was 24.7% examined by Giemsa staining and 25.6% by flow cytometry, that of the control cells was 1.3% and 0% respectively. CONCLUSION: MG132 can inhibit the proliferation of dopaminergic PC12 cells and lead to apoptosis. The disfunction of proteasome may do harm to the existence of dopaminergic cells. ......