For that, we incubated the MEFs with eGFP-labeled exosomes, derived from MCF-7 breast cancer cells that express a doxycycline-inducible eGFP-syntenin fusion protein (Supplemental Fig. 4), and quantified the amount of fluorescence (eGFP) inside (i.e. internalized by) the cells, using confocal microscopy (Fig. 4b). The gene discussed is SDCBP; the disease is breast carcinoma.