Exposure of U937 cells to CH11 anti-Fas Abs activates both caspase-2L and caspase-8.

The U937 cells were exposed to 50 ng/mL CH11 Ab (+ 0.8 μg/mL CHX) for indicated times. The ability of cell extracts to cleave VDVAD-AFC (▪) and IETD-AFC (░) substrates was measured and the expressions of procaspase-2L, procaspase-8, and caspase-8 active fragments were studied by Western blot. An antihuman HSC70 Ab was used for loading control.