Effect of Ilantide on nuclear factor κB activation induced by interleukin 1β. HEK cells that overexpressed interleukin 1 receptor type I (IL-1RI) or IL-6 receptor (IL-R6) were first treated with the Ilantide peptides, control peptides, IL-1 receptor antagonist (IL-1Ra) or soluble IL-1RI (sIL-1RI), after which IL-1β-induced nuclear factor κB (NF-κB) or IL-6-induced signal transducer and activator of transcription 3 (STAT3) activation was determined by enzyme-linked immunosorbent assay through the induction of a reporter gene that expressed secreted embryonic alkaline phosphatase under the control of the interferon β minimal promoter fused to five NF-κB binding sites. (A) IL-1β-induced NF-κB activation was inhibited by IL-1Ra. (B) IL-1β-induced NF-κB activation was inhibited by sIL-1RI. (C) IL-1β-induced NF-κB activation was inhibited by Ilantide-t. (D) IL-1β-induced NF-κB activation was inhibited by Ilantide-m. (E) Control peptides with scrambled or reversed sequences did not inhibit IL-1β-induced NF-κB activation. (F) Ilantide-t did not inhibit IL-6-induced STAT3 activation. The results from four independent experiments are expressed as percentage ± SEM, in which control cells treated with either IL-1β or IL-6 alone were set at 100%. **P < 0.01 and ***P < 0.001 compared with IL-1β-treated or IL-6-treated controls (one-way analysis of variance followed by Newman-Keuls post hoc test).