ITGAM and cancer: Furthermore, MAMs interact with CTCs via integrins such as vascular cell adhesion molecule-1 (VCAM-1) to form protective clusters that improve cancer cell survival during migration.186 Gr-1 + CD11b+ monocytes promote the establishment of metastatic tumor cells in the lungs, particularly in breast tumor-bearing mice, through mechanisms such as PDGF-BB-induced angiogenesis and CCL9 production,187 which support tumor cell survival188 (Fig. 3).