Fig. 5

CIB1 depletion in combination with docetaxel or TRAIL induces caspase-independent cell death. Pre-treatment using a pan-caspase inhibitor, z-VAD-fmk (z-VAD) helped to determine contributions of caspase-independent, non-apoptotic cell death mechanisms induced by the combination treatments. Control or CIB1-depleted cells were pretreated with vehicle (DMSO) or 50 µM z-VAD-fmk (z-VAD) for 24 h before adding a 10 nM docetaxel or b 10 ng/ml TRAIL for 48 h. The concentrations for docetaxel and TRAIL were chosen because we observed a sufficient increase in cell death and caspase-8 activity when combined with CIB1 depletion. Percent cell death was quantified as in Fig. 1, represented by mean ± SD, *P < 0.05 (n = 3). z-VAD inhibits caspase-8 but does not affect PARP activation or the expression of a marker of paraptosis, Alix. Lysates prepared from control or CIB1-depleted cells in a and b treated with c docetaxel or d TRAIL were probed with for PARP, cleaved caspase-8, cleaved caspase-3, Alix, CIB1, and vinculin (loading control). Western blot is representative of 3 independent experiments