ESR1 and endometriosis: Detection of ectopic endometrial epithelial and stromal cells in TE was most often performed with ER, PR, and CD10, but recently interferon-inducible transmembrane protein 1 (IFITM1) for stromal [28] and Pax8 for epithelial cells [31] seem to be also highly sensitive markers for extra-pelvic endometriosis.