Figure 5

Vpr promotes proteasome-mediated protein degradation of Cdc25B and Cdc25C. (A) Synchronized G1/S HeLa cells treated with HU or transduced with Adv-Vpr were collected at indicated time, and then subjected to Western blot analysis using anti-Cdc25B or anti-Cdc25C antibody, respectively (a). β-actin was used as a loading control. The relative intensity of the Cdc25B (b) or Cdc25C (c) protein levels to β-actin were determined by densitometry. The results presented are the average of three independent experiments. (B) Synchronized HeLa cells were pre-treated with specific siRNA against Chk1 or treated with 50 μm MG132 at 0 hour and collected at the indicated time. The protein level of Cdc25B was detected by Western blot analysis. (C) Synchronized HeLa cells were treated with 50 μm MG132 at 0 hour and collected 11 hours after treatment. The protein level of Cdc25C was detected by Western blot analysis (a). HeLa cells were pre-treated with specific siRNA against Chk1, which were then synchronized at G1/S boundary by DT treatment. HU or Vpr treated cells were collected 11 hours after DT release. The protein level of Cdc25C was detected by Western blot analysis using indicated antibodies (b).