The interaction between FXR and estrogen receptor (ER) activated by CDCA induced apoptosis of the positive ER cell line MCF-7 [10], while the negative ER cell line MDA-MB-231 was not sensitive to FXR [36], which indicated that FXR could induce apoptosis of breast cancer cells through the estrogen pathway. The gene discussed is NR1H4; the disease is breast cancer.