<unk>  has been shown to exert its effects by binding to the<unk>  receptor <unk> oR).<unk> O binds to the<unk>  receptor on the red cell progenitor surface and activates a JAK2 signalling cascade. This initiates the STAT5, PIK3 and Ras MAPK pathways. This results in differentiation, survival and proliferation of the erythroid cell. SOCS1, SOCS3 and CIS are also expressed which act as negative regulators of the cytokine signal. High level<unk>  receptor expression is localized to erythroid progenitor cells. While there are reports that<unk> O receptors are found in a number of other tissues, such as heart, muscle, kidney and peripheral/central nervous tissue, those results are confounded by nonspecificity of reagents such as anti-EpoR antibodies. In controlled experiments, a functional<unk> O receptor is not detected in those tissues. In the bloodstream, red cells themselves do not express<unk>  receptor, so cannot respond to<unk> O. However, indirect dependence of red cell longevity in the blood on plasma<unk>  levels has been reported, a process termed neocytolysis. In addition, there is conclusive evidence that<unk> O receptor expression is upregulated in brain injury.
Erythropoietin
Granulocyte colony-stimulating factor
Thyroglobulin
Granulocyte-macrophage colony-stimulating factor
Hemopoietic growth factor
Growth hormone
Parathyroid hormone
Colony-stimulating factor