FIG. 6.
CD95 receptor clustering and internalization require caspase 8 activation. (A) Induction of CD95 clustering on BJAB vector transfectants or BJAB cells expressing FADD-DN as described in Fig. 2C. (B) Induction of CD95 clustering of SKW6 vector-transfected cells or SKW6 cells stably expressing Bcl-2 as described in Fig. 2C. (C) SKW6-vec (•) or SKW6-Bcl-2 (○) transfectants were treated with 1 μg of anti-CD95 per ml for different periods of time. δΨm was determined as described in Materials and Methods. (D) MCF7-Fas cells were treated with either 20 or 50 μM caspase inhibitor zVAD-fmk (polycaspase inhibitor), zDEVD-fmk (caspase 3 or 7), or zIETD-fmk (caspase 8). After treatment, cells were incubated with anti-CD95 and kept on ice (time 0) or stimulated for 60 min (60′) at 37°C. Receptor localization was determined as described in Fig. 2C.