Figure 5

E boxes in the BRCA1 promoter are required for BRCA1 activation by constitutively expressed c-Myc. MCF-7 or MDA-MB-231 cells (A or C, respectively) were transiently co-transfected with Myc-GFP expression vector along with the BRCA1 promoter (pCYL42, FL) or its derivates with E box nucleotide substitutions (X, Y, or XY) as described in methods. Luciferase activities from cell lysates were determined 48 hours after transfection. The fold changes were normalized to the vector control and the full-length BRCA1 promoter activities set as 1. *: p < 0.01. The activation of a promoter/reporter construct containing six tandem E boxes (E box-luc) by constitutively expressed Myc-GFP was used as a control [B or D (MCF-7 or MDA-MB-231, respectively)]. Bars show mean ± SD. *: p < 0.01 as each indicated column compared to the FL column in A or C, and to -luc column in B or D.