Table 5.

Inhibitors of p38 (SB203580) and MEK1 (PD098059) Cumulatively Inhibit the TNF-α Production of J774A.1 Macrophages Stimulated with Virulence Plasmid–cured Y. enterocolitica (WA-C).

Pretreatment*		TNF-α production‡
		No bacteria		WA-C
Nothing		37 ± 4		1,625 ± 126
SB203580		59 ± 16		752 ± 121
PD098059		47 ± 10		680 ± 150
SB203580 + PD098059		45 ± 8		49 ± 5

^* J774A.1 cells were either not pretreated or pretreated for 30 min with the compounds SB203580 (10 μM), PD098059 (50 μM), or the two compounds together. Thereafter, half of the samples were challenged by the addition of virulence plasmid–cured yersiniae (WA-C).  

^‡ The TNF-α activity in the cell culture supernatant (dilution 1:120) was measured 4 h after the onset of infection with strain WA-C, using a cytotoxic assay performed with the TNF-α–sensitive fibroblast cell line L929.