Inhibition of the CXCR4-CXCL12 axis, on the other hand, can sensitize cancer cells to chemotherapy or radiotherapy by inhibiting the interaction between the CXCR4-expressing tumor cells and stromal cells, resulting in decreased cancer cell protection by the CXCL12 releasing stromal cells [19–21]. The gene discussed is CXCR4; the disease is cancer.