SP1 and breast cancer: To identify previously unreported transcription factors regulating VEGF transcription, we used a VEGF promoter (from −2304 to +73 bp)-luciferase (VEGF-Luc) reporter to screen a transcription factor genome-wide full-length cDNA-transfection (GFC-transfection) array, consisting of 704 transfection-ready cDNA plasmids, and identified some transcription factors that stimulated the reporter gene expression in ZR75-1 breast cancer cells (Figure 1A, 1B and data not shown), such as GATA1 and the previously reported transcription factors SP1 [13] and HIF1α [14].