CXCR4 and myocardial ischemia: Ang-1 has been shown to have a critical role in the maintenance of hematopoietic stem cell in the bone marrow through its binding to the Tie-2 receptor.[13]The hematopoietic stem cell cytokine SDF-1α and it receptor CXCR-4 have been identified as the central signaling axis that regulates recruitment of hematopoietic stem cells into the injured area of myocardial ischemia and in improvement of cardiac function after MI [14].