Figure 3. (A and C) schematic representation of the human miR200s promoters on chromosome 1 (A) and on chromosome 12 (C) cloned in pGL3 basic reporter vector. Numbers indicate the distance from the transcription start site (TSS) represented as an arrow. Black boxes indicate the position of potential myb binding sites (MBS). The longest construct (wt) and the deletion mutants (Mut) generated for each promoter are represented in each scheme. (B and D) Luciferase assays were performed in HEK293 cells co-transfecting the indicated reporter vectors with the pcDNA3HA (empty vector, white bars) or the pcDNA3-c-mybHA (c-myb expressing, black bars) expression vectors. Transfection efficiency was normalized by co-transfecting a renilla luciferase-expressing vector. Assays were performed 48 h after transfection. Fold activation of each reporter vector co-transfected with pcDNA3HA was arbitrarily set to 1. Luciferase assays data are reported ± standard deviation. Statistical significance was calculated by two-tailed Student t test. ** P ≤ 0.01. n.s. = not significant. Experiments were performed twice in triplicate.