Migration assays were performed as described previously (19 (link)). Briefly, cells (5 × 104) were plated in medium without serum in the upper well of a transwell chamber of a 24-well transwell with 8-μm pores (BD Biosciences), placed in a bottom chamber containing medium supplemented with 10% fetal bovine serum. After 48 h, the membranes were fixed and stained with haematoxylin solution, and migration was quantified by counting ten random fields under a light microscope (400×). The mean value was calculated from data obtained from three separate chambers.