FIG. 4.

Effect of MG132 on gene expression regulated by early, intermediate, and late promoters. (A) Early promoter. HeLa cells were inoculated with vpJ2R-CAT for 1 h at 4°C and then with the indicated concentrations of MG132 at 37°C for 6 h. Cells were harvested and CAT activity was determined. CAT activity is indicated as the percentage of substrate conversion normalized to the activity with no inhibitor. (B, C) Intermediate and late promoters. The protocol was similar to that described for panel A, except that cells were infected with vpG8R-CAT or vpF17R-CAT and that activity was determined 8 h after infection. (D) Effect of virus multiplicity. HeLa cells were infected with vpF17R-CAT virus with the indicated virus multiplicity (PFU/cell) as described for panel C, and CAT activity was determined.