Plates with transwell inserts (Corning, New York, USA) which were pre-coated with 20 μg/μL Matrigel (BD Biosciences, New Jersey, USA) were used to test cell invasion. The upper chambers with 200 μL serum-free media were added with 50,000 siRNA or lentivirus transfected cells. In parallel, 900 μL DMEM media with 10% FBS was added to lower chamber of each well. After incubation for 24 h at 37°C, cells from the upper surface of the membrane were removed with a cotton swab and the penetrated cells were fixed with 4% methanol for 5 min and then stained with 0.1% crystal violet for 30 min. Six fields of cells were captured and counted randomly under inverted microscope (Nikon, Tokyo, Japan) at ×20 magnification in each well. Upper chambers without Matrigel were used to test cell migration.