In the peri-ductal stroma, peptidyl-prolyl cis/trans isomerase (Pin1), a gene overexpressed in breast tumors [32], was up-regulated following exposure to the estrogens while the tripartite motif-containing 29 (Trim29), a gene suppressed in prostate and breast cancer [33], [34] was down-regulated in an ERα dependent manner. The gene discussed is PIN1; the disease is breast cancer.