SFN-induced HDAC3 loss is independent of caspase-3 activity. (A) HCT116 cells were treated with various concentrations of SFN and the whole cell lysates were immunoblotted at 24 and 48 h for HDAC3, PARP/cleaved PARP, and cleaved (active) caspase-3. Asterisk, position of HDAC3 cleavage product reported by Escaffit et al. ; arrows, position(s) of the cleavage product(s) of PARP and caspase-3. (B) Loss of full-length HDAC3 detected with antibodies specific to the C- and N-terminal portions of the HDAC3 protein; no corresponding increase was detected for the HDAC3 cleavage product (asterisk). Whole cell lysates also were immunoblotted for p21WAF1and PARP. (C) HCT116 cells were treated with a cell-permeable pan caspase inhibitor (z-VAD(OMe)-FMK, z-VAD), 1 h before DMSO or SFN (15 μM) exposure, and the whole cell lysates obtained at 24 h were immunoblotted for HDAC3, HDAC6, PARP and caspase-3. CTR, control.