CXCR4 and leukemia: Given that CXCL12/CXCR4 signaling is deregulated in patients with myelodysplastic syndromes (MDS) and leukemias [26] and the recent discovery of CXCR7 as an additional receptor for CXCL12, the aim of the present work was to investigate CXCR7 expression and function in MDS and leukemias, and to elucidate whether CXCR7 affects CXCR4 response to CXCL12 in these malignances.