EMSA of putative κB sites from the "human enhancer like" sequences of the mouse NOS-2 promoter. The mouse -103 κB sequence was compared with the oligonucleotide sequences containing putative κB sites (identified as 'κB-like sites') in EMSAs with nuclear protein extracts from mouse peritoneal macrophages. Equal amounts of labeled oligonucleotide were used for each assay. C: nuclear extracts from control macrophages; LPS: nuclear extracts from macrophages treated with 200 ng/ml of LPS for 1 h. Ex: Extracts from LPS-treated cells in the presence of a 50-fold excess of unlabelled oligonucleotide. The bands corresponding to the p50/p65 and p50/p50 complexes are indicated. n.s. corresponds to the front and non specific binding in the EMSA.