Table 4. The effect of a MEK inhibitor PD98059 and a p38 MAPK inhibitor SB203580 on the antiapoptotic effect of TNF-α in human eosinophils.

		Apoptosis (% of control)
	TNF-α (ng/ml)	Solvent control	Inhibitor
PD98059 (10 µM)	0.1	94±8	96±3
	1	90±8	96±2
	10	84±8	84±7
	100	79±8	82±7
SB203580 (1 µM)	0.1	95±3	95±2
	1	92±4	93±2
	10	92±4	88±2
	100	89±3	80±3

Eosinophils were preincubated with the solvent control (0.5% DMSO) or the indicated inhibitor for 30 min and thereafter with various concentrations of TNF-α for 40 hours. Apoptosis was assessed by measuring the relative DNA content of propidium iodide-stained cells by flow cytometry. Results are means ± SEM of 4 (PD98059) or 10 (SB203580) independent determinations using eosinophils from different donors. The control value in the absence of TNF-α is set as 100%. The percentage of apoptotic eosinophils in the absence of TNF-α and PD98059 was 63.5±2.5 and in the presence of TNF-α (100 ng/ml) it was 50.2±5.3 (n = 4). The percentage of apoptotic eosinophils in the absence of TNF-α and SB203580 was 58.0±5.8 and in the presence of TNF-α (100 ng/ml) it was 50.9±5.1 (n = 10).