Transwell Migration and Invasion Assay

For the migration assay, 500 μl complete medium was supplemented to the lower chamber of the Transwell chamber, and then 5 × 10⁵ BC cells were resuspended in serum-free medium and subsequently added to the upper chamber of the Transwell chamber (the pore of the Transwell was 8.0 μm, Corning, Corning, NY, USA and Labselect, Chongqing, China). Upon a 24-h incubation in an incubator with 5% CO₂, the cells were fixed by 75% ethanol and stained with crystal violet solution. For the invasion experiment, 50 μl of Matrigel diluted by serum-free medium was firstly supplemented into the upper chamber of the Transwell chamber, which was placed at 37 °C for 1 h. The rest steps were the same as the migration experiment.