Figure 6.

Functionality of p21^(waf1/cip1) promoter constructs. Reporter gene assays were performed with extracts from MCF-7 cells that were transiently transfected with luciferase reporter constructs containing regions 1, 2, 3, 7, 12C or 19 of the human p21^(waf1/cip1) promoter (A) or wild-type and mutated forms of region 7 (B) and an expression vector for human VDR. The dinucleotides below the RE sequences indicate the point mutations that were introduced into promoter region 7. Cells were treated for 16 h with either solvent, 100 nM 1α,25(OH)₂D₃ or 100 µM fluorouracil. Relative luciferase activity is shown. Columns represent means of at least three experiments and bars indicate standard deviations. Two-tailed Student's t-tests were performed to determine the significance of the reporter gene induction in reference to solvent controls (^*P < 0.05).