Withaferin A (WFA) potently inhibits NF-κB activation by preventing the tumor necrosis factor-induced activation of IκB kinase β via a thioalkylation-sensitive redox mechanism. Withaferin A binds to the intermediate filament (IF) protein, vimentin with antitumor and antiangiogenesis activity. Withaferin A is a steroidal lactone isolated from Withania somnifera.