Presence of platelet proteins in MPs of EPC cultures. (A) Transmission electron microscopy. Image of MPs harvested from the conditioned medium of EPC cultures. (B) Proteomic analysis. Product ion spectra of doubly charged tryptic peptides identified as the platelet integrin αIIb (GQVLVFLGQSEGLR) and integrin β3 (SILYVVEEPECPK).