(A-C): Bandshift assays showing constitutive activation and DNA binding specificity of AP-1 in esophageal cancer. (A) nuclear proteins (10 μg) extracted from esophageal tumors (1-5) and their adjacent normal tissues were incubated with γ32P-labeled double stranded AP-1 binding probe and run on 4.5% non-denaturing PAGE. (B) uniform binding of Oct-1 in normal adjacent tissues and cancer. (C), binding specificity of AP-1 in esophageal cancer biopsies was evidenced by adding 100× molar excess of unlabeled homologous competitor, AP-1 oligo in competition with heterologous probe Oct-1 as indicated in methods. Arrows indicate the position of specific retarded bands.