E2 can induce Jag1 and Notch1 expression in breast cancer MCF7 cells; increased Jag1 is abrogated by ER antagonist treatment, suggesting an ER-dependent mechanism corroborated by the discovery of imperfect oestrogen-responsive elements in the 5′ region of Notch1 and Jagged1 genes [124]. This evidence concerns the gene JAG1 and breast cancer.