AS cells were pretreated with parthenolide or vehicle (placebo) for 1 h and then stimulated with TNFα/IL-1β for the indicated time. Nuclear extracts were prepared and then analyzed by EMSA for both transcription factors NFκB and AP-1. Representative autoradiograph of EMSA for (A) NFκB activation and (C) for AP-1 were presented. Summary graph of data for NFκB (B) and AP-1 (D) activation determined by densitometry from 4 time course experiments (n = 5 in each time point and condition), mean ± SEM are shown. Solid bar, placebo; and open bars, parthenolide. Parthenolide pretreatment inhibited the activation of (B) NFκB at 15, 30 and 60 min p = 0.003, p = 0.003 and p = 0.004, respectively), and (D) AP-1 at 30 min (p = 0.004).