The second aim was to find out whether tamoxifen, a selective oestrogen receptor modulator (SERM) and fulvestrant, an anti-oestrogen devoid of agonist activity, were able to abrogate the proliferative effects of E2 on normal breast tissue from women carrying BRCA1 and BRCA2 mutations or who were, otherwise, at increased risk of developing breast cancer. The gene discussed is BRCA1; the disease is breast cancer.