Figure 4

It is unlikely that -575 p27 (5'-untranslated region (5'UTR) of p27 gene) contains any cryptic transcription factor binding sites. (a) Schematic drawing (adapted from references [5,6]) of the pGL3-control-p27-5'UTR-luciferase reporter plasmid. (b) Summary of the experimental protocol. (c) The ER-negative MDA-MB 231 cells were transfected with -575 p27 (p27-5'UTR) and then either vehicle or actinomycin D (0.5 μg/ml) [29] was added to the medium. One hour after the addition of these compounds, the cells were exposed to vehicle, tamoxifen (1.076 μM) or 4-hydroxytamoxifen (1.032 μM) for 24 hours. All assays were performed in triplicates and the transfection experiments were repeated three times.