Erythropoietin (EPO) is a 34-39 kda secreted glycoprotein belonging to the Type I cytokine superfamily. EPO is mainly produced by cells in the kidneys (interstitial renal tubular fibroblasts) and liver (hepatocytes and Ito cells), and hypoxia can upregulate EPO production. Erythropoietin is the main hormone that regulates the proliferation and differentiation of red blood cells and maintains the physiological level of circulating red blood cell volume. The amino acid sequence homology between mouse erythropoietin and rat erythropoietin is 94%, and the amino acid sequence homology with human erythropoietin is 80%. In addition to its role in promoting erythropoiesis, EPO also acts on various non hematopoietic cells, playing its role as a survival and proliferation factor. EPO can stimulate the proliferation of myoblasts while inhibiting their differentiation, leading to the expansion of the progenitor cell population. EPO is a tissue protective factor that can protect nervous, cardiovascular, and renal tissues from ischemic and toxic damage.