Figure 3: Ischemic brain injury and erythropoietin neuroprotection. EpoR expression by neurons mediates a direct neuroprotective EPO response. EPO production in astrocytes and neurons and EPO crossing the blood-brain barrier that is compromised during injury contribute to increased EPO in the local microenvironment. Endothelial cell EPO response can contribute indirectly to neuroprotection via improved oxygen delivery and secretion of neurotrophic factors.