Fluorescence assays for GPR30 binding and activation with 2 and 3. a) GPR30 competitive binding of E2, 17α-E2, 2, and 3 with fluorescent estradiol derivative E2Alexa using permeabilized COS7 cells. b) Calcium mobilization assay for GPR30 and ERα in transfected COS7 cells vs concentration of E2, and complexes 2 and 3 (each at 10, 100, and 1000 nM).