FIG. 4.

Effects of pp71 on accumulation cell surface MHC class I cannot be attributed to induction of apoptosis. Film image of electrophoretically separated cell lysates reacted with antibody to caspase 3 or actin. Cultures of U373:CIITA cells in six-well plates were mock infected, exposed to 30 PFU of the AD169 strain of CMV per cell, or exposed to15 PFU of Adβgal or 100 PFU of Adpp71 per cell. In parallel, cultures of U373:CIITA cells in six-well plates were exposed to 0.2 μM staurosporine. Cells exposed to virus were harvested and solubilized 48 h after infection, and cells exposed to staurosporine were harvested at the times indicated. One hundred micrograms of protein from each lysate was subjected to electrophoresis in a denaturing polyacrylamide gel. Proteins were transferred to nitrocellulose sheets and reacted with anti-caspase 3 antibody. Nitrocellulose sheets were then stripped and reprobed with antibody to actin as described in Materials and Methods. Integrated optical density determinations were made for each relevant band visualized on the film images, and the ratio of caspase 3 band density to actin band density is indicated for each lane below the film image.