CXCR4 and breast cancer: The CXCL12/CXCR4 axis is a critical molecular determinant in the bone homing of hematopoietic stem cells during foetal life and marrow transplantation.5 On the basis of the hematopoietic model, several authors have hypothesised that prostate and breast cancer cells may use a similar pathway to localise to the bone marrow.6,7 The functional role of the CXCL12/CXCR4 axis in NETs has recently been investigated.