FIG. 2.
TVBS1, TVBS3, and TVBT proteins induce apoptosis via the caspase pathway by a mechanism involving their cytoplasmic death domains. Human 293 cells were transfected with plasmid DNA encoding wild-type and mutant TVB proteins or instead with a control plasmid pBK-CMV (Stratagene). Cells were incubated with or without the caspase inhibitor zVAD-fmk (zVAD). The numbers of apoptotic nuclei associated with each cell population was determined by fluorescence microscopy after Hoechst staining by using a Nikon TE-200 microscope. Ten fields of each cell population were studied. The experiments were performed in triplicate, and the standard deviations of the data obtained are shown.