Separate E boxes within the minimal 5′PDβ2 bind E47. (A) Nuclear extracts from the P5424 cell line were incubated with radiolabeled probes to the putative E boxes: E-I (lanes 1-5) and E-II (lanes 6-10) alone (lanes 1 and 6), or in the presence of 100-fold molar excess of the indicated unlabeled competitors (lanes 2-5 and 7-10). Specific nucleoprotein complexes are indicated (filled arrows). (B) Probes to the E-I site were incubated with nuclear extracts from P5424 (lanes 1-4), Rag2-/- thymocytes (lanes 5-8), or Jurkat (lanes 9-12) alone (lanes 1, 5, and 9) or in the presence of the indicated Abs (lanes 2-4, 6-8, and 10-12). Ab-supershifted complexes are indicated (empty arrows).