Effect of the CED-3/ICE–like protease inhibitor Z-VAD.fmk on DNA fragmentation in B-CLL cells. Cells from patients 5 and 9 were incubated for 24 hours with 10 μmol/L dexamethasone in the presence or absence of 200 μmol/L Z-VAD.fmk. Z-VAD.fmk was added 1 hour before dexamethasone administration. DNA was extracted and subjected to agarose gel electrophoresis as described in Materials and Methods. Similar results were obtained with cells from patients 7 and 8.