CD63 and cancer: To further confirm whether exosomal wtEGFR protein can be internalized by sensitive mutEGFR cancer cells, exosomes were isolated from CM of H1299 cells by differential ultracentrifugation and characterized by Western blot analysis (positive marker: CD63, TSG101, Alix; negative marker: Calnexin; as well as transmembrane protein of EGFR) (Fig. 2a), Nanoparticle Tracking Analysis (NTA) (Fig. 2b) and Transmission Electron Microscope (TEM) (Fig. 2c).