BID and prostate cancer: To determine whether sanggenol L induces apoptosis through caspase cascades in human prostate cancer cells, we examined levels of procaspases-3, -8, and -9, as well as cleaved-PARP, Bid, Bax, and Bcl-2 by performing western blot analysis and examined the influence of z-VAD-fmk (a caspase inhibitor) using an SRB assay (Figure 3).