Similar gradients are likely engaged in the heart, supported by experimental evidence linking SDF-1 and CXCR4 activation to fibrocyte recruitment and myocardial fibrosis [76], as well as by patient data suggesting that circulating SDF-1 can promote fibrocyte migratory behavior in atrial fibrillation [78]. Here, CXCR4 is linked to Myocardial fibrosis.