Recognizes a protein of about 37kDa, which is identified as Erythropoietin (EPO). Erythropoietin is a secreted, glycosylated cytokine hormone composed of four alpha helical bundles. It is the primary factor responsible for regulating erythropoiesis during steady-state conditions and in response to blood loss and hemorrhage in the adult organism. Erythropoietin is synthesized by the kidney and stimulates the proliferation and maturation of bone marrow erythroid precursor cells. The protein is found in the plasma and regulates red cell production by promoting erythroid differentiation and initiating hemoglobin synthesis.