cells attached onto the upper side of the transwell filter were removed by a cotton stick. The migrated cells attached onto the bottom side of the transwell filter were fixed with 4% PFA (Sigma), and visualized with 0.5% crystal violet staining (Sigma). Five different areas of each chamber were randomly selected for photography with × 5 objective (Olympus). The average cell number/area was calculated for each chamber. Biological Triplicates with technical triplicates (n=9) were performed for each cell line.
