EMSA validation of EBF binding sites: A: The figure displays EMSAs in which binding of EBF to a mb-1 promoter EBF site is competed for by the inclusion of 300 or 1000-fold molar excess of unlabelled oligonucleotides that correspond to the predicted motifs. The name of the gene and the position of the motif is given in the figure. (m) indicates mouse and (h) human. "EBF" shows the position of the DNA/protein complex, and "Probe" indicates the position of free DNA. See supplementary information for a detailed description of the sites. B: The mb-1 promoter EBF site interacts specifically with EBF protein in a pre-B cell nuclear extract. The figure displays an autoradiogram in which a labelled EBF binding site from the mb-1 promoter has been incubated with nuclear extracts from 40EI pre-B cells and competitors or antibodies as indicated. EBF denotes the bound EBF protein and EBF-SS the super-shifted complex obtained by the addition of the EBF reactive antibody to the reaction mixture.