Aim:To determine whether deguelin can regulate the expression of nuclear factor kappa B (NF-κB) binding protein (IκBα) in U937 human leukemia cells and Raji human B lymphoma cells.Methods:The localization of IkBαprotein was investigated by using an immunofluorescence method.The expression of IκBα and NFκB/p65 proteins in Raji and U937 cells were investigated by using Weste blotting.Apoptosis was detected through annexin V/PI double-labeled cytometry.Results: IκBα localized in the cytoplasm in untreated and deguelin-treated cells.Atier treatment with tumor necrosis factor α (TNF-α) or deguelin plus TNF-α for 15 min,there was a substantial reduction in the amount of IκBα protein.The expression of IκBαwas downregulated by deguelin in Raji and U937 cells.Deguelin induced apoptosis in U937 cells.Conclusion:Deguelin inhibited the expression of IκBα protein in U937 and Raji cells.The anti-proliferative activity of deguelin is related to the signal pathway of NF-κB.