However, ovarian surface epithelial cells are more commonly considered PAX8-negative, and occasional PAX8-positive cells in the ovarian surface epithelium are thought to be FTSEC or endometrial cells that migrate to the ovarian surface [116,134], leaving PAX8-positive endometriosis cells as the main cell of origin for clear cell and endometrioid ovarian cancers. The gene discussed is PAX8; the disease is endometriosis.