Furthermore, to evaluate whether the ER-α binding site plays biological roles in transcriptional activation of miR-196a response to E2 stimulation, we constructed the pGL3 luciferase reporter vectors containing wild type or mutant type with mutation of seed sequence of the ER-α binding site in miR-196a promoter region, then tested luciferase activities of BC cells with or without E2 treatment. Here, ESR1 is linked to breast cancer.