CXCR4 and myocardial ischemia: Using diabetic db/db mice subjected to myocardial ischemia, the present study investigates whether overexpression of Ang-1 promotes recruitment of hematopoietic progenitor cells into ischemic sites and whether this leads to attenuation of myocardial ischemic injury through SDF-1α/CXCR-4 signaling.