FIGURE 8.

Effect of deleting GC-rich (Sp1) elements on SFN regulation of p21^Cip1 promoter activity in the context of the full-length promoter. A, shown is a sequence map of the proximal region of the p21^Cip1 promoter. The six GC-rich (Sp1) sites are identified. The numbers indicate nucleotide position relative to the transcription start site at +1. B, keratinocytes were transfected with 0.5 μg of each p21^Cip1 promoter luciferase reporter plasmid or with empty vector (EV) lacking p21^Cip1 promoter sequences. After 24 h, the cells were treated with 20 μm SFN. After an additional 24 h the cells were harvested and assayed for luciferase activity. The respective plasmid names identify the deleted Sp1 sites (e.g. Δ1, Δ2, Δ1–6, etc.).