CXCR4 and neoplasm: The mobilization of dormant tumor cells from the PVN to the peripheral blood is mediated by C-X-C motif chemokine Receptor 4 (CXCR4) inhibition, suggesting that the axis CXCR4/CXCL12 (CXC motif chemokine 12) is crucial to anchor dormant tumor cells in the PVN (Figure 1).