Promoter activity after pretreatment with parthenolide and/or stimulation by TNFα/IL-1β. AS cell lines were transfected with a plasmid-driving expression of the firefly luciferase reporter under control of IL-8 promoter. Then AS cells were pretreated with 40 μM parthenolide or vehicle for 1 h and then stimulated with TNFα/IL-1β for the 3 and 6 h. At the indicated time media was collected and subject to ELISA to determine IL-8 production. Cells were washed and then assayed for luciferase activity. Firefly luciferase activity was normalized against a constitutively expressed Renilla luciferase reporter. Results are expressed as relative luciferase activity above control cells transfected and pretreated with DMSO.