Chromatin peptides induce apoptosis in HeLa cells. A: apoptosis level measured by DNA fragmentation ELISA after 12, 24 and 48 hours of treatment with 5 μg/ml of peptide pool. (black bars) control cells; (grey bars) treated cells. B: analysis of proteins involved in apoptosis induced by chromatin peptides. Whole cell extracts were prepared from treated (24 h) and untreated HeLa cells. The same amount of proteins was assayed by PAGE and western blotting using antibodies specific for: (a) cleaved caspase-7, (b) cleaved caspase-9, (c) Bax, (d) Bcl-2 and (f) cleaved PARP. C: densitometric analysis of the immunoblots. The values are expressed as percentage of the control.