Unlike CXCR4 in which a small molecule antagonist Plerixafor (Selleckchem) is available, only anti-CXCL16 neutralizing antibody is available for blocking the CXCR6–CXCL16 interaction.22 Indeed, CXCR4 antagonist treatment significantly reduced the ability of cancer cells to migrate to brain metastatic CAF aggregates, while CXCL16 antibody treatment was less effective than CXCR4 antagonist treatment alone (Fig. 5b, c). Here, CXCR4 is linked to cancer.