Tax-induced NF-κB and SP-1 binding activity.

Nuclear extracts from JPX-9 cells, treated with or without CdCl₂ (20 μM) for the indicated time periods, were mixed with either NF-κB (A) or SP-1 ³²P-labeled probes (B) (lanes 1-6). Competition assays were performed with nuclear extracts from JPX-9 cells treated with CdCl₂ for 72 hours. Where indicated, 100-fold excess amounts of each specific competitor oligonucleotide were added to the reaction mixture with labeled probes NF-κB (A, lanes 13-17) or SP-1 (B, lanes 7-11). Supershift assay of NF-κB DNA-binding complexes in the same nuclear extracts was performed as in Figure 6 (A, lanes 7-12). Arrowheads show the DNA-binding complexes supershifted by antibodies.