CXCR4 and cancer: Multiple antagonists of CXCR4 including bicyclams (AMD3100) and T22, as well as peptide analogues designed for the N-terminal region of CXCL12, such as TN14003, CTCE-9908, and ALX40-4C are currently used to target CXCR4 in various cancers [115,116,117].