One hypothesis is that these molecules occupy an allosteric site within CXCR4 not previously identified which does not interfere with CXCL12 or M1 signaling, but which may be partially required by CXCR4 and some as yet unidentified ligand to signal the intracellular milieu in breast cancer cells. The gene discussed is CXCR4; the disease is breast carcinoma.