CRYSTAL STRUCTURE OF THE ER-ALPHA LIGAND-BINDING DOMAIN (Y537S) IN COMPLEX WITH THE OBHS-BSC ANALOG, 3-FLUOROPHENYL (1R,2R,4S)-5-(4- HYDROXYPHENYL)-6-(4-(2-(PIPERIDIN-1-YL)ETHOXY)PHENYL)-7- OXABICYCLO[2.2.1]HEPT-5-ENE-2-SULFONATE AND 3-METHYL-6-PHENYL-3H- IMIDAZO[4,5-B]PYRIDIN-2-AMINE