Micrococcus- and sPGN-induced transcription of the gene for IL-8 in HEK293 cells expressing TLR2 is inhibited by dominant negative (dn) MyD88, IRAK, TRAF2, TRAF6, NIK, and IKK. HEK293 cells were cotransfected with plasmids expressing TLR2, CD14, and pIL8(wt)CAT and with dominant negative mutant forms of the following signal transduction molecules: MyD88, IRAK1, IRAK2, TRAF2, TRAF6, or the appropriate control vector (CV) (A) and NIK, IKKα, IKKβ, IκBΔN, or the appropriate control vector (B). All plasmids were used at the same concentrations as in previous experiments. Cells were stimulated as described in the legend to Fig. 1 for 16 h, and cell lysates were assayed for CAT activity. The results were calculated as described in the legend to Fig. 3 and are means ± standard errors from three experiments.