CXCR4 and metastatic neoplasm: (28) reported that CXCR4 and SDF-1 are highly expressed in primary rectal tumors of patients presenting with metastatic disease, while radiochemotherapy and bevacizumab further upregulate CXCL12 expression; however, there were no differences in CXCR4 or CXCL12 expression at baseline between patients who had (n=9) vs did not have (n=30) a pCR.