ICAM1 and neoplasm: To confirm whether aggregate dispersal in the presence of M2a macrophages was indeed dependent on cell-cell contact and to ascertain a role for adhesion in the process, we used flow cytometry to assess the surface expressions of CD11a, CD11b and CD11c integrins on macrophages; these proteins are expressed on leukocytes and interact with ICAM-1 on tumor cells (Figure 5A).