Effects of pretreatment with calpeptin or DEVD-fmk on the content of μ-procalpain/μ-calpain (top panel) and procaspase-3 (lower panel) in resting and A23187-treated platelets. Platelets were preincubated with no inhibitor or calpeptin (50 μg/mL) or DEVD-fmk (25 μg/mL) and were lysed by the addition of SDS, immediately or after stimulation with A23187 for 10 or 20 minutes. Shown are immunoblots of 1.5 × 10⁷ platelets stained with B27D8 anti–μ-calpain (top panel) or C31730 anti–caspase-3 (lower panel) MoAb.