PGR and breast cancer: The expression of FXR also correlates with other proteins such as Ki-67, cyclin D1, and p27 in postmenopausal women, as well as other breast cancer biomarkers such as progesterone receptor (PR), GATA Binding Protein 3 (GATA-3), a coactivator of ER, amplified in breast cancer-1(AIB-1), cytokeratin (CK)-8/18 and mucin 1 (MUC1) [110].