Phorbol-ester-induced Activation of the NF- B Transcription Factor Involves Dissociation of an Apparently Cytoplasmic NF- B/Inhibitor Complex

In eukaryotic cells, many genes respond in their rate of transcription to extracellular stimuli. Changes in gene expression in response to such agents as steroid hormones, growth factors, interferon, tumor promoters, heavy metal ions, and heat shock were shown to be modulated through distinct cis-acting DNA-sequence elements (for review, see Hatzopoulos et al. 1988). The most important sequences are those called enhancers (for review, see Schlokat and Gruss 1986), which display great positional flexibility with respect to the gene they control (Banerji et al. 1981; Fromm and Berg 1983), and promoters, which are confined to the 5′-noncoding region of the gene (for review, see McKnight and Tjian 1986). Both cis-acting elements contain multiple binding sites for sequence-specific DNA-binding proteins (for review, see Hatzopoulos et al. 1988; Wingender 1988). The demonstration of DNA-protein interaction in vivo (Ephrussi et al. 1985), in vitro competition experiments (Schoeler and Gruss 1985), and the mutational...