Western blotting was performed as previously described (8 (link)). In brief, protein lysates (10–30 µg) were separated via sodium dodecyl sulfate-polyacrylamide gel electrophoresis and were subsequently transferred onto polyvinylidene difluoride membranes (EMD Millipore). The membranes were first incubated overnight with primary antibodies specific for E-cadherin (1:10,000; cat. no. 20874-1-AP), vimentin (1:5,000; cat. no. 10366-1-AP), BTG1 (1:1,000; cat. no. 14879-1-AP), CD63 (1:1,000; cat. no. 25682-1-AP), TSG101 (1:3,000; cat. no. 14497-1-AP) and GAPDH (1:6,000; cat. no. 60004-1-Ig) that had been diluted in a 5% low-fat milk-TBS with 0.1% Tween-20 solution and then with a horseradish peroxidase-conjugated secondary antibody (1:3,000; cat. no. PR30009). The labeled protein bands were visualized using enhanced chemiluminescence (Beyotime Institute of Biotechnology), and band intensities were semi-quantified using ImageJ software (version 1.49p; National Institutes of Health). All primary and secondary antibodies were purchased from Wuhan Sanying Biotechnology.