Concentration/response dependence of increasing amounts of p38 inhibitor SB202190 or dominant negative MKK6 kinase mutant MKK6(Ala) on TNF-–induced MCP-1 promoter activity. HUVEC were transfected with a MCP-1 promoter/enhancer luciferase construct as described in Materials and Methods. (A) Thirty-six hours later, cells were exposed to increasing concentrations of p38 inhibitor SB202190 as indicated and stimulated with 1 ng/mL TNF- 30 minutes later for another 12 hours. Luciferase activity was determined as described in the legend to Fig 7. (B) HUVEC were cotransfected with the MCP-1 promoter/enhancer construct and increasing amounts of MKK6(Ala) as indicated and stimulated with 2 ng/mL TNF- 36 hours later for another 12 hours. Relative luciferase activity is expressed as fold stimulation.