Suppression of anti-Fas antibody–induced apoptosis in BJAB K1 transfectants. (A) Aliquots of cells were incubated for 24 hours with the anti-Fas antibody CH-11, stained with Hoechst 33342, and examined microscopically for morphologic features of apoptosis. Apoptosis rates in 4 wells were significantly lower in BJABK1 cells than in BJABK1m and BJABXS cells treated with 20 or 40 ng/mL CH-11 (*P < .01). The error bars indicate standard deviation. Similar results were obtained in 2 independent experiments. (B) Time-dependent killing effect in transfected BJAB cells. Cells were treated with 50 ng/mL CH-11, stained with Hoechst 33342, and examined microscopically for morphologic features of apoptosis. Apoptosis rates were significantly lower in BJABK1 cells than in BJABK1m and BJABXS cells at 12, 24, and 48 hours (*P < .05 for all comparisons). Similar results were obtained in 2 independent experiments.