ABSTRACT
NF-κB is a ubiquitous transcription factor, which is a heterodimer consisting of proteins of the Rel/NF-κB family. It exists in the cytoplasm as an inactive form due to its association with a specific inhibitor protein family, designated as IκB, which inhibits the nuclear translocation of NF-κB by binding to nuclear localizing signal peptides of NF-κB (reviewed in Refs 1,2). Treatment of cells with a wide variety of stimulants including LPS has been shown to free NF-κB from IκB, most likely as a result of phosphorylation and/or proteolysis of IκB protein (1–8). Free NF-κB then translocates to the nucleus and binds to the κB consensus motif (GGGRNNYYCC), which exists in the enhancer/promoter regions of genes coding for various cytokines such as IFN-β (9), GM-CSF (10), G-CSF (11), IL-6 (12), or TNF-α (13), for cell surface proteins such as MHC class I (14) or II (15) or Fey receptor (16), and for cellular enzyme such as inducible nitric oxide synthase (iNOS) (17,18).
