Transwell insert for 24 well plate

The transwell insert for 24-well plate (8 μm-pore size, Corning, New York, USA) was used to measure the migratory and invasive ability of cells. For transwell migration assays, HeLa cells (2.5 × 10⁴) were seeded into the transwell insert (upper chamber) with serum-free medium after NTP exposure for 10, 20 or 40 s, and the culture medium with 10% FCS was added in the lower chamber (the space between the well bottom and the insert) for chemo-attractant. The invasion assays were performed similarly except that the upper chambers of 24-well cell culture inserts were coated with 200 mg/ml of Matrigel (BD Biosciences, Bedford, MA). After 24 h incubation, the insert was taken out and the cells were fixed with 4% paraformaldehyde for 30 min and stained with 1% crystal violet. The non-invading cells were carefully removed from the upper surface of the insert membrane with cotton wool. The number of cells migrated to the lower surface of the membrane was determined by counting 10 randomly selected fields of view under the microscope. Data were expressed as the percentage of invasion of treated cells as compared to the control cells.

The transwell insert for 24-well plate (8 μm-pore size, Corning, NY, USA) was used to measure the migratory and invasive ability of cells. For transwell migration assays, cells (2.5 × 10⁴) with shMETTL7B or negative control shRNA were seeded into the transwell insert with serum-free medium and the culture medium with 10% FBS was added in the lower chamber for chemo-attractant. The invasion assays were performed similarly except that the upper chambers of 24-well cell culture inserts were coated with 200 mg/ml of Matrigel (BD Biosciences, Bedford, MA). Following culture for 48 h at 37˚C, the cells in the bottom chamber were stained with 0.1% crystal violet (Beyotime Biotech, China). The cells were then evaluated by a light microscopy (CK40; Olympus Corporation, Tokyo, Japan) at the magnification at ×100. Images were captured, then the cells were counted randomly in five fields and the average was calculated.