VCAM1 and myeloid sarcoma: Natalizumab is a humanized monoclonal antibody that selectively binds to the α4-integrin component of adhesion molecules found on lymphocytes, monocytes, and eosinophils; thus, natalizumab inhibits the interaction of α4β1 with VCAM-1, and because VCAM-1 is expressed on inflamed cerebrovascular endothelial cells, α4β1 is believed to be the critical target of natalizumab in preventing leukocyte migration into the central nervous system in MS [28].