CD81 and esophageal squamous cell carcinoma: Meanwhile, the expression of exosome-specific marker proteins (CD63, CD81, and HSP70) was detected in ESCC cell-derived exosomes instead of the exosome-negative marker GM130 (Figure 5B), and qRT-PCR data showed that miR-620 was highly expressed in the miR-620-Exo group (Figure 5C).