CXCR4 and myocardial ischemia: Here, we demonstrate that 1) myocardial ischemia triggers the release of circulating MMP-2, which inhibits SDF-1α and CXCR4 release; 2) SDF-1-induced migration of CD34+ cells towards cardiomyocytes was inhibited by MMP-2in vitro; 3) IP inhibited MMP-2 release, thereby increasing both SDF-1α and CXCR4 levels, resulting in a higher level of CD34+ cell mobilization 3 days post ischemic injury inin vivo condition; 4) IP induced VEGF secretion in the second window of cardioprotection.