Gel mobility shift analysis of NF-κB recognition sites in the promoters of IL-6 and IL-8, using nuclear extracts from IL-17-stimulated FLS. Changes in the amount of NF-κB in the nuclear extracts isolated from two patients with RA after stimulation of the extracts with 10 ng/ml of IL-17 or IL-1β were tested by gel mobility shift assay of radiolabeled oligonucleotide probes representing the NF-κB sites in the promoter of (a) IL-6 and (b) IL-8. Arrows indicate probe bands shifted by NF-κB binding. Nuclear extracts of IL-1β-stimulated FLS were used as positive controls. Lane 1, unstimulated cells; Lane 2, stimulated with IL-17; lane 3, stimulated with IL-1β. FLS, fibroblast-like synoviocytes; RA, rheumatoid arthritis.