One plausible mechanism involves the contact between integrin α4/β1/αvβ3, Macrophage-1 antigen (Mac-1), and CC-chemokine ligand 2 (CCL2) present on the cell membranes of macrophages [96,97] and vascular cell adhesion molecule-1 (VCAM-1) present on the cell membranes of BVECs [98,99] and glioma cells [100]. Here, VCAM1 is linked to central nervous system cancer.