ITGA4 and neoplasm: Taken together, (i) tumor-exosomes bind and are taken-up in vitro and in vivo by T cells, NK, B cells, DC, Mφ and granulocytes; (ii) leukocyte subpopulations differ in tumor-exosome uptake, which for ASML-exosomes is highest for PEC and lowest for granulocytes; (iii) differences in tumor-exosome uptake depend on the availability of leukocyte ligands for exosomal receptors, where CD11b, CD11c, CD44, CD49d, CD54 and CD62L are engaged in ASML-exosome binding; (iv) as previously shown[28], exosomes bind via tetraspanin complexes.