In vitro studies have used cDNA microarrays to confirm changes in gene expression in E2-treated PEO1 cells (an ER-positive, estrogen-responsive ovarian cancer cell line); the activation of ERα-mediated transcription was shown to be responsible for the observed changes in gene expression, as well as the estrogen-driven growth of epithelial ovarian carcinoma, whereas ERβ played no meaningful role (110). The gene discussed is ESR1; the disease is ovarian cancer.