To investigate the role of OPN and CD44 opsonization in cellular uptake, cilengitide (CL) was used to inhibit the interaction between OPN and integrins54,55, and free hyaluronic acid (HA) was pretreated with tumor cells for competitive binding with CD44 to impede the nanovesicle-CD44 interaction56,57. Here, CD44 is linked to neoplasm.