CASP9 and endometriosis: In order to better understand the effects of PGC-1α on the proliferation, apoptosis, and gene expression profiles of human endometrial stromal cells, this study aims to perform a more thorough and in-depth analysis of the expression patterns of PGC-1α and its related signaling molecules (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.