In agreement with these results obtained from K1, K2, W1 and W2 cells in culture, VEGFa expression is also reduced more than 60% in Ncoa1 knockout mammary tumors in Ncoa1−/− × Tg(MMTV-PyMT) mice versus Ncoa1 WT mammary tumors in Tg(MMTV-PyMT) mice. This evidence concerns the gene NCOA1 and breast cancer.