FIG. 3.

M protein expression induces activation of caspase-3. (A) HeLa cells (open circles) or BHK cells (closed circles) were transfected with the indicated amounts of M mRNA for 24 h. The cells were analyzed for caspase-3 activity as described in the legend to Fig. 2. The amount of caspase-3 activated is expressed in arbitrary fluorescence units. (B) BHK cells (closed circles) or HeLa cells (open circles) were transfected with 30 ng of M mRNA for the indicated times. Cells were lysed and assayed for caspase-3 activity. The data represent the average ± the standard deviation of three experiments.