4.5. Transwell Migration Assay

The migration capability of endometrial cancer cells was assessed using Transwell^® cell culture inserts from Corning (Corning, NY, USA). In brief, 3 × 10⁴ cells were seeded onto the upper chamber in 300 µL of serum-free medium containing ISL (1, 5, and 10 μM) or 10 ng/mL of TGF-β1. The cell migration ability at 48 h was then assessed. Cells that migrated through the basement membrane filter were fixed with 100% methanol for 10 min and stained with Giemsa stain (Sigma-Aldrich, St. Louis, MO, USA). Non-migrated cells on the upper surface of filter were gently scrubbed with cotton. The lower face of the membrane was examined. The crystal violet was extracted with 10% acetic acid, and its absorbance was determined at 600 nm and photographed under a microscope.