CXCR4 and inflammation: Indeed, while several reports demonstrate that SDF-1 and/or its receptors promote repair of the injured kidney, liver, limb, brain and retina [17–23] by mobilizing endothelial progenitor cells to injury sites [22, 24, 25] or upregulating vascular endothelial growth factor (VEGF) and other angiogenic factors [26], in adult lung disease models, SDF-1/CXCR4 signaling potentiates lung inflammation and CXCR4 antagonism attenuates lung inflammation and injury [27, 28].