Overexpression of SNAI2 /Slug increases glioblastoma migration and invasion. A) Scratch wound healing assay for human U251 glioblastoma cells overexpressing a control vector or a SNAI2/Slug vector. Cells were photographed at 0 hours and 24 hours after scratch application. The dotted lines indicate the original edges of the scratch defect. B) Transwell migration assay for human U251 glioblastoma cells overexpressing SNAI2/Slug or a control vector. 10% serum was used as a chemoattractant. The cells that migrated through the membrane were stained and counted under direct microscopy. Slug-expressing glioblastoma cells migrated faster than the control cells (asterisk indicates P < 0.00001, t-test). C) 3-dimensional Matrigel assay for human U251 glioblastoma cells overexpressing a SNAI2/Slug vector or a control vector. After 24 hours, cells that invaded through the matrix were fixed, stained with H&E and counted under direct microscopy. Data shown are mean ± SEM. Glioblastoma cells overexpressing Slug showed greater invasiveness than did control cells (asterisk indicates P < 0.001, t-test).