CXCR4 and neutropenia: Interestingly, neutropenia of the mutant Cxcr4+/1013 mice occurs in the context of normal maturation of the granulocyte lineage [41] in support of the fact that transient normalization of blood counts upon CXCR4 blockade or patient’s infections [43] likely arises from disturbed neutrophil trafficking rather than from a production defect [41].