Effects of resveratrol and curcumin treatment on IL-1β-induced IκB kinase activation. Serum-starved primary human chondrocytes were pre-treated with (a) 50 μM resveratrol or (b) 50 μM curcumin for 4 hours and then co-treated with IL-1β (10 ng/ml) for the indicated times. Whole cell extracts were immunoprecipitated with an antibody against IκB kinase (IKK)-α and analysed by an immune complex kinase assay. To examine the effect of curcumin on the expression level of IKK proteins, whole cell extracts (500 ng protein per lane) were fractionated by SDS-PAGE and examined using western blot analysis with anti-IKK-α and anti-IKK-β antibodies. Data shown are representative of three independent experiments. The results demonstrate that resveratrol does not affect IL-1β-induced IKK activation.