Effects of R115777 on the induction of apoptosis in U266 cells. Cells were cultured with R115777 at 1.0 × 10^-8 M and then examined using flow cytometry. (A) There were 3 populations revealed by 2-color flow cytometric analysis using FITC-annexin V and 7-amino-actinomycin D (7AAD): viable (lower left; a), early apoptotic (lower right; b) and both late apoptotic and necrotic cells (upper right; c). U266 cells cultured without R115777 for 72 hours are mostly viable (90.7%) (a). (B) U266 cells treated with R115777 at 1.0 × 10^-8 M after incubation for 72 hours showed viable (56.5%), early apoptotic (20.2%) and late apoptotic and necrotic (22.6%) cells.