DLX2 binds to TrkB proximal promoter elements isolated by chromatin IP. (A) EMSA were performed using recombinant DLX2 protein and radiolabeled R1-pro oligonucleotide probes, with cold competition using unlabeled probe (A, lane 3) and specific DLX2 antibody ‘supershift’ assays (A, lane 4). Lane 1: labeled R1-pro alone. Lanes 2–5: labeled R1-pro probes were incubated with rDLX2 (2), rDLX2 and unlabeled R1-pro (3), rDLX2 and anti-DLX2 (4) and rDLX2 and a control antibody (5). (B) EMSA was also done using embryonic retinal nuclear extracts and radiolabeled R1-pro oligonucleotide probes containing either the first (TrkB motif 1, lanes 1–5) or second (TrkB motif 2, lanes 6–10) candidate homeodomain binding sites, with cold competition using unlabeled probe (B, lanes 3 and 8) and specific DLX2 antibody ‘supershift’ assays (B, lanes 5 and 10). Lanes 1, 6: labeled R1-pro alone. Lanes 2–10: labeled R1-pro probes were incubated with nuclear extract (2,7), nuclear extract and unlabeled TrkB motifs (3,8), nuclear extract and a control antibody (4,9) or nuclear extract and anti-DLX2 (5,10).