Erythropoietin also known as epo,hematopoietin, or hemopoietin, is a glycoprotein hormone that controls erythropoiesis, or red blood cell production. It is a cytokine (protein signaling molecule) for erythrocyte (red blood cell) precursors in the bone marrow. Erythropoietin is used to treat anemia resulting from kidney failure or cancer treatment. It is considered to be an alternative to blood transfusions.