Role of caspases in TNFα-induced apoptosis and Mcl-1 turnover. (A) Neutrophils were incubated in the presence of cycloheximide (10 μg/mL) alone, or with TNFα (10 ng/mL) or GM-CSF (50 U/mL) in the absence (□) or presence of either MG132 (50 μM, ▩) or Z-VAD-FMK (Cas In 50 μM, ■). After 3-hour incubation, samples were removed and apoptosis was determined by morphology. Side panel shows representative cytospins. Typical result of 3 separate experiments. (B) Neutrophils were incubated as described for panel A but after 2 hours and 5 hours, protein lysates were analyzed by Western blotting for levels of Mcl-1 or GAPDH. Typical result of 3 separate experiments.