FIG. 4.

E4orf4 induces apoptosis in transfected 293 cells. (A) 293 cells were transfected with 5 μg of pEGFP-C1 and 5 μg of either the CMV vector or the CMV vector expressing wild-type E4orf4. The cells were fixed 48 h posttransfection, stained with DAPI, and subjected to fluorescence microscopy at a magnification of ×600. Each field was photographed twice with filters suitable for detection of the GFP and DAPI staining. The arrowheads mark the nuclei of transfected cells, detected by the presence of the GFP. (B) Experiments were carried out as for panel A. For each experiment, at least 100 transfected cells were counted, and the percentage of nuclei manifesting apoptotic phenotypes, as seen in panel A, was calculated. The graph shows the mean of five experiments.