*4.3. Endometrial Tissue Collection and RNA/Protein Isolation*

Endometrial (eutopic) tissues from control patients (EuN), eutopic tissues from endometriosis (peritoneal endometriosis, "endo") patients (EuE), and ectopic endometriotic tissues (EcE) from endo patients were removed during laparoscopy/laparotomy by a qualified physician. Biopsy fragments were immediately placed in RNA*later* solution (Cat No: 76104, Qiagen, Gaithersburg, MD, USA) and subsequently stored in a freezer at −80 ◦C. RNA extraction from 100 mg of tissue (eutopic and ectopic) was carried out using Qiazol Lysis Reagent (Cat No: 79306, Qiagen, Gaithersburg, MD, USA). Tissues were homogenized using zirconium oxide beads in a Bullet Blender® homogenizer (SKU: BBX24, Next Advance, Troy, NY, USA) and RNA was isolated using the Qiagen miRNeasy Mini Kit following the manufacturer's recommendations (Cat No: 217004, Qiagen, Gaithersburg, MD, USA). The quantity and quality of RNA were measured using the NanoDrop 2000 spectrophotometer (Cat No: ND2000, Thermo Scientific, Waltham, MA, USA). Protein lysates from 50 mg of tissue was homogenized in RIPA buffer prior to protein estimation by a modified Lowry method [77].
