Figure 1. 5′ deletion analysis of the Ccna1 promoter reveals a repressor element upstream of -120 bp with respect to the transcription start site (TSS).

Chimeric constructs of the Ccna1 promoter-luciferase reporter are schematically represented on the category-axis. The upstream and downstream endpoints of each fragment are indicated with respect to the TSS, which is indicated by a bent arrow. Constructs were tested for transcriptional activity in GC-4spc and NIH3T3 cells as described in the Methods section. The luciferase activity obtained for the pGL-Basic vector, in which a functional promoter was absent, was set at 1.0 and all other luciferase activities were expressed as fold of the values obtained for pGL-Basic. All experiments were performed in quadruplicate, and the means ± standard deviations of luciferase expression from independent experiments are shown. In all experiments the luciferase activity of pRL-CMV, Renilla luciferase expressing under CMV promoter was used as an internal control.