ESR2 and endometriosis: Objective: The present study was designed to comprehensively analyze the expression profiles of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), estrogen-related receptor-α (ERRα), estrogen receptor-β (ERβ), interleukin-6 (IL-6), cysteinyl-aspartic acid-specific protease-3 (caspase-3), and cysteinyl-aspartic acid-specific protease-9 (caspase-9) in endometriosis tissues.