Erythropoietin is available as a drug. Why would athletes abuse it?

Question

Erythropoietin is available as a drug. Why would athletes abuse it?

Answer 1

  It won't act as a drug it simply increases the amount of oxygen in the blood and allows one to expend more energy.

Answer 2

It stimulates the production of red blood cells, and as a result an athlete's blood would be able to carry more oxygen to feed working muscles, which would be a competitive advantage. The harder way to get this advantage naturally is to train at altitude in which the thinner air (less oxygen) stimulates the production of red blood cells.