FIG. 5.

TBP binding site negatively regulates the PCNA initiator element. Two copies of either wild-type proximal TRE (2X −21 to −1), Δ PIR, or Δ PDR sequences in a luciferase reporter plasmid were cotransfected with the pRL-SV40 Renilla reporter plasmid into 293 cells. Luciferase activity was normalized to Renilla luciferase activity from the same well. Error bars represent the standard errors of the means for three independent experiments performed in duplicate. *, significant difference in normalized luciferase activity between cells transfected with 2X Δ PIR and cells transfected with empty plasmid (Student t test; P < 0.05).