Fig 2.

 TRAIL activates the caspase cascade in Hsp70-expressing CCRF-CEM cells. (A) Cells were incubated at 37°C with 100 ng/mL TRAIL for 0, 6, 12, or 18 hours prior to harvest. Equal amounts of protein were separated on a 13% SDS-PAGE gel and transferred to nitrocellulose membranes. Membranes were probed with specific antibodies that detect both the proform and cleavage products of human caspase-8, caspase-9, caspase-7, or caspase-3, or Bid. (B) Clone 7 cells were preincubated for 1 hour with 50 μM z-VAD-fmk in DMSO or an equivalent concentration of DMSO, and then incubated with 100 ng/mL TRAIL for 18 hours at 37°C. Apoptosis was evaluated by scoring nuclear morphology. The means and standard deviations of 3 independent experiments performed in duplicate are shown. Statistical analysis by Student's t-test; *P < 0.05 vs TRAIL alone