Transwell Migration and Invasion Assays

Cell migration and invasion were assessed using the Millipore 24-well Millicell Chamber with pore size 8 mm (Millipore). For the migration assay, 8,000 cells in DMEM without FBS were added to the upper chamber of the insert. For the invasion assay, 50,000 cells in DMEM without FBS were added to the upper chamber pre-coated with Matrigel (Sigma). DMEM with 20% FBS was placed in the lower chamber. Cells were incubated for 8 h for the migration assay and 20 h for the invasion assay. Then, cells were fixed and stained with 0.1% crystal violet, and non-invading cells were removed with cotton swabs. The number of cells on the lower surface of the chamber membrane was counted under a microscope with a 20× objective in five random fields.