To evaluate the effect of genetic CXCR4 reduction on metastasis development, murine melanoma B16 cells were injected into the tail vein of C57BL/6 CXCR4+/+ and CXCR4+/− mice in the presence of the CXCR4 inhibitor, Plerixafor (previously named AMD3100). Here, CXCR4 is linked to melanoma.