Exoab cd9a 1

Whole-cell lysates and EV samples were separated via 10% SDS-PAGE, and Western blotting was conducted as previously described [19 (link)]. The following antibodies were used: a mAb against TSG101 (1:1000, Santa Cruz Biotechnology, sc-794), a mAb against CD9 (1:1000 System Bioscience EXOAB-CD9A-1), a mAb against BiP (1:1000; catalog no. 3177, Cell Signaling); a mAb against PERK (1:1000; catalog no. 5683, Cell Signaling), and a mAb against GAPDH (1:10 K; Santa Cruz Biotechnology, sc-32233). Protein bands were detected with an ECL chemiluminescence kit (Millipore, USA), and were imaged with a ChemiDoc ™ XRS + instrument (BioRad, USA).

Cell culture medium was centrifuged at 500 g for 10 min, then the supernatant was centrifuged at 20 000 g for 20 min. The supernatant was transferred to a fresh tube, filtered through a 0.22 µm filter and pelleted by ultracentrifugation (Beckman Optima L‐100 XP, Beckman Coulter) at 100 000 g for 70 min. Exosome pellets were washed in a large volume of PBS and recovered by centrifugation at 100 000 g for 70 min. The particle concentration and size distribution of the purified exosomes were determined using NTA in ZetaView (Particle Metrix). The morphology and size of the exosomes were determined using SEM. Purified exosomes were characterized by western blotting using antibodies against TSG101 (Abcam, ab125011), CD9 (System Biosciences, ExoAB‐CD9A‐1), Calnexin (Cell Signaling Technology, 2679), Flotillin1 (Proteintech, 15571‐1), and CD81 (Proteintech, 66866‐1).