Decreased expression of procaspase-2L prevents anti-Fas Ab–mediated procaspase-8 activation.

(A) Western blot analysis of procaspase-10 and procaspase-8 expression in U937/neo and U937/AS3 cells at indicated times (x-axis; hours) after anti-Fas Ab treatment. HSC-70 expression level is used as protein loading control. One representative of 3 independent experiments is shown. (B) Kinetics of IETD-AFC hydrolysis in U937/neo (●), U937/AS3 (○), U937/AS1 (■), and U937/AS2 (▵) cells. Enzyme activities were measured as initial velocities and expressed as relative to control untreated cells.