PECAM1 and nasopharyngeal carcinoma: Treatment with exosomes derived from EBV-positive NPC cells but not EBV-negative NPC cells, resulted in a significant decrease in TJ protein levels in HUVECs, accompanied by a marked decrease in endothelial markers such as cluster of differentiation 31 (CD31) and an increased expression of mesenchymal biomarkers such as α-SMA, Vimentin, and S100A4 (Fig. 1E).