Phosphatidylserine exposure assessed by Annexin V-labeling after apoptosis induction in control and Scott cells. Cells, treated for 72 h by 200 nM A23187 or 10 μM SKF 96365, were loaded with the fluorochrome Fluo-3 (3 μM) and annexin V-biotin (5 μl at 0.5 mg/ml) and labeling was achieved with phycoerythrin-conjugated streptavidin. Results are expressed as phycoerythrin fluorescence versus cell number. The cell populations with high annexin V labeling correspond to those with high Fluo-3 fluorescence (Fig. 4). One representative experiment out of four performed likewise is shown.