CD9 and colorectal carcinoma: By detection of the tetraspanin family within exosomes derived from the three CRC cell lines by western blotting, CD63, CD9, and CD81 were detected within exosomes derived from HCT-15 cells; CD9 and CD81 were detected within exosomes derived from SW480 cells; and CD81 was detected within exosomes derived from WiDr cells (Fig. 1B).