CXCR4 and thyroid cancer: The action of tetrac on chemokine expression is generally downregulation (37), but in contrast, chemokine ligand CXCL10 and receptor CXCR4 mRNAs are found in abundance in tetrac-treated human breast and thyroid cancer cells (37) CXCL10 can serve as an attractant for macrophages and T cells (38, 39), as well as being pro-apoptotic (40).