Complex formation between putative Caudal binding sites in the dE2F promoter and GST-Cad. Radiolabeled double-stranded E2F-Cad oligonucleotides were incubated with 20 µg of GST-Cad in the presence or absence of the indicated competitor oligonucleotides. Lanes 1, 6 and 11, GST only. Lanes 2, 7 and 12, binding without competitor. Lanes 3, 4, 8, 9, 13 and 14, unlabeled competitor DNA with the wild-type E2F-Cad sequences (wt). Lanes 5, 10 and 15, unlabeled competitor DNA with mutants having three base changes in E2F-Cad sequence (mut). E2F-Cad1, E2F-Cad2 and E2F-Cad3, oligonucleotides containing the Caudal sites 1–3 of the dE2F gene promoter.