This peculiarity of AIB1 serves as a mechanism by which it influences the growth of hormone-dependent breast cancer as suggested by the observation that depletion of AIB1 affects estrogen-dependent cell proliferation and survival in ER-positive MCF-7 human breast cancer cells, causing a reduction of MCF-7 xenografts growth in mice [64, 65]. This evidence concerns the gene ESR1 and breast carcinoma.