Effects of resveratrol and curcumin treatment on IL-1β-induced IκBα degradation. Serum-starved human chondrocytes were pre-treated with 10 ng/ml IL-1β alone for 4 hours, or with 100 μM N-Ac-Leu-Leu-norleucinal (ALLN) for 30 minutes, or pre-treated with 50 μM resveratrol, 50 μM curcumin or 100 μM ALLN alone for 4 hours and then co-treated with IL-1β (10 ng/ml) for 8 hours. Other serum-starved chondrocytes were pre-treated with 50 μM resveratrol or 50 μM curcumin alone for 4 hours and then co-treated with IL-1β (10 ng/ml) for 8 hours. Some cultures were left untreated and evaluated after 12 hours. Cytoplasmic extracts (500 ng protein per lane) were fractionated and then subjected to western blotting with phosphospecific IκBα antibody. The data demonstrate that resveratrol (but not curcumin) inhibits IL-1β-induced IκBα degradation. Data shown are representative of three independent experiments. The same membrane was re-blotted with antibodies to β-actin.