CDDO activation of the extrinsic apoptosis pathway in CLL B cells.

CLL B cells were cultured in the presence or absence of 1 μM CDDO, or they were electroporated with caspase-8, with or without CrmA (10 μM) or XIAP-BIR3 (20 nM), along with PE-BSA (4 μg/mL) fluorescent marker protein. Effector caspase activity was determined by CaspaTag assay (n = 5). (A) Representative FACS histogram is presented, showing CaspaTag fluorescence (y-axis) versus forward scatter (x-axis) for the gated 7-AAD⁻, PE-BSA⁺ population. The horizontal line indicates the cutoff of cells with activated effector caspases. (B) Data from 5 experiments were averaged (± SE), showing relative levels of caspase activity (MFI).