FIGURE 4. DSG induced UHRF1 protein degradation through the ubiquitin-proteasome system. a-b DU145 or C4-2 cells were treated with DSG for 40 h, and then treated with cycloheximide (CHX, 50 μg/mL). The proteins were harvested at the indicated time points, and UHRF1 levels were assessed by immunoblotting. β-actin was used as a loading control. The bands were quantified using densitometry analysis software.c-d Cells were treated with DSG for 42 h, followed by treatment with MG132(50 μM) for 6 h. UHRF1 protein was assessed by immunoblotting.e-f The plasmids expressing HA-ubiquitin and UHRF1-His were co-transfected to DU145 or C4-2 cells. The cells were treated with DSG at different doses for 48 h, and then followed by treatment with or without MG132(50 μM) for 6 h. UHRF1 was immunoprecipitated with anti-His antibody, and the polyubiquitylated UHRF1 was assessed with anti-HA antibody.