Erythropoietin (/ɪˌrɪθroʊˈpɔɪᵻtən/ or /ɪˌrɪθroʊpoʊˈɛtɪn, -rə-, -ˈiː-, -tən/; from Greek: ἐρυθρός, erythros 'red' and ποιεῖν, poiein 'make'), also known as EPO, hematopoietin, or hemopoietin, is a glycoprotein hormone that controls erythropoiesis, or red blood cell production.