CXCR4 and diabetes mellitus: The presence of diabetes in rats or intravitreal injection of HMGB1 in normal rats significantly upregulates the levels of mRNAs encoding SDF-1/CXCL12 receptor CXCR4, as well as levels of HIF-1, EGR-1, TK-2, and CXCL12/CXCR4 proteins in the chemokine axis [57].