*2.6. Western Blotting*

Proteins were detergent-extracted from EVs and subjected to sodium dodecyl polyacrylamide gel electrophoresis (SDS-PAGE; 10 μg/lane) and transferred to nitrocellulose membrane for Western blot detection using antibodies to CD9 (1:500; Abcam, Cambridge, MA, USA), flotillin-1 (1:200; BD Biosciences, San Jose, CA, USA), Tsg101 (1:500; Thermo Fisher Scientific), fibronectin (FN1) (1:1000; Abcam), FN1 EDA domain (1:250; Sirius Biotech, Genoa, Italy), FN1 EDB domain (1:100; Sirius Biotech), pan-keratin (1:500; Cell Signaling Technology, Danvers, MA, USA), proteasome subunit alpha type-6 (PSMA6, 1:500; ABclonal Inc, Woburn, MA, USA) or ribosomal protein S27a (RPS27A, 1:500; ABclonal). Blots were developed using IRDye 800 CW secondary antibodies (LI-COR Biosciences, Lincoln, NE, USA) in conjunction with Odyssey CLx Imaging (LI-COR Biosciences).
