IHC studies were performed using the standard streptavidin/peroxidase staining method, as described previously 22 (link). The following antibodies were used: anti-Rac1(1:1000), anti-Snail1(1:200), anti-N-cad (1:500), anti-Twist1(1:1000) (Abcam, Cambridge, UK), anti-E-cad, and anti-Vim (Maxin, Fuzhou, China). All known positive sections served as positive controls. Negative mouse serum and PBS were used instead of the first antibody as a negative control and blank control, respectively.