Downregulation of superoxide release in TNF-–induced neutrophils and reversal by zVAD-fmk. Neutrophils incubated with or without TNF- plus cycloheximide (TNF/CHX) for the indicated time in the absence or presence of indicated concentrations of zVAD-fmk were stimulated with either FMLP (100 nmol/L), OZ (1 mg/mL), or PMA (20 ng/mL) for 15 minutes at 37°C. Superoxide generated during that 15 minute period was determined by cytochrome c reduction. Data shown represent the average values from three separate experiments performed in duplicate.