Effect of curcumin on IκBα phosphorylation and IκB kinase.
Curcumin inhibits IκBα phosphoryalation and IκB kinase. (A-B) First, 5 × 106 U266 cells per 2.5 mL were treated with curcumin (50 μM) for the indicated times. Cytoplasmic extracts were prepared for checking the level of phosphorylated IκBα by Western blotting (panel A), or IKK was immunoprecipitated and the kinase assay was performed (panel B) to check the IKK activity (upper panel), or Western blotting was performed for the analysis of total IKKα and IKKβ proteins in cytoplasmic extracts (lower panel). (C) Cytoplasmic extracts were prepared from 5 × 106 U266 cells, IKK was immunoprecipitated, and kinase assay was performed in the absence or presence of the indicated concentration of curcumin (upper panel). Lower panel indicates the amount of glutathione S–transferase (GST)–IκBα protein stained with Coomassie blue in each well in the same dried gel.
