CXCR4 and stroke disorder: Hypoxic preconditioning of MSCs resulted in the up-regulation of HIF-1α, VEGF, erythropoietin (EPO), stromal-derived factor-1 (SDF-1), and C-X-C chemokine receptor type 4 (CXCR4), thus potentiating their pro-angiogenic capacities in stroke rodents [78].