Although multiple transcription factors including HIF1α, AP-1, NF-κB, Sp1 and ERα have been reported to regulate VEGFa expression [38–40, 50, 51], our study is the first to show NCOA1, a transcriptional coactivator, can robustly and simultaneously coactivate two transcription factors, HIF1α and AP-1, to augment VEGFa expression and breast tumor angiogenesis. This evidence concerns the gene FOS and breast neoplasm.