Fig. 1.

TOPBP1 is degraded in a proteasome-dependent manner in Ad12- but not Ad5-infected cells. (A) Effect of Ad infection on expression levels of proteins involved in ATR activation. HeLa cells were mock-infected or infected with the indicated viruses. Cells were harvested and prepared for Western blotting at the indicated time points using the appropriate antibodies. (B) Effects of the proteasome inhibitor MG132 on TOPBP1 expression levels in Ad12-infected cells. HeLa cells were mock-infected or infected with Ad12, in the presence or absence of 10 μM MG132 added 2 h after infection. Cells were harvested and prepared for Western blotting at the indicated time points, and MRE11 was used as a positive control.