ESRRA and ovarian cancer: Since SKOV‐3 which has defective ERα receptor also demonstrated similar BPA‐induced sphere formation as in HEYA8 which consists of functional ERα receptor, we hypothesized that BPA may induce the growth of CSCs and sphere formation in an ER‐independent manner through alternative receptors, which are ERRα, ERRγ and GPR30, that have key roles in ovarian cancer progression.21