The exosomes isolated from the supernatants of tumor cells cultured in two different conditions (buffered and pH 6.5 medium) were analyzed using nanoscale flow cytometry (Cytoflex) for the presence of typical exosomal CD81 and CD9 markers, respectively labeled in allophycocyanin (APC) and in phycoerythrin (PE). The gene discussed is CD9; the disease is neoplasm.