Hexamethylene bisacetamide (HMBA)-induced caspase-independent cell death.

CCRF (A, C) and A7 (B, D) CEM cells were treated with 10 mmol/L HMBA or 5 ng/mL vincristine (Vin) for 48 hours. In some wells, cells were pre-incubated for 4 hours with 40 μmol/L ZFA-fmk or ZVAD-fmk. Cells were assayed by trypan blue exclusion as described in “Materials and methods” (A, B) or were stained with Hoechst 33 258 and visualized by confocal microscopy and scored for apoptotic nuclei as described in “Materials and methods” (C, D). Protein lystates were prepared from cells treated as above and separated by SDS-PAGE. Western blots were performed using polyclonal anti-PARP antibody (e). The active 118-kD and inactive 89-kD forms of PARP are indicated.