Effect of the cytochrome P450 inhibitor SKF 525A on cell death. Control and Scott B lymphoblasts were treated with SKF 525A (10 μM) for 48 or 72 h in the absence (a) or in the presence of calcium ionophore A23187 (200 nM) (b). The degree of apoptosis was determined by measurement of hypodiploid DNA using propidium iodide (0.1 mg/ml). Values are mean ± SEM of at least 6 independent determinations. *P < 0.05 versus control cells.