While many cytokines are known for their inflammatory action, there is a growing interest in the tissue-protective effects of some cytokines. The prototypic tissue-protective cytokine is EPO. Initially described as neuro-protective, it is beneficial in animal models of ischemic and other types of injury. Scientists had to overcome the notion that EPO had only erythropoietic actions, was only produced by the kidney, and that its receptor was only present in erythroid progenitor cells. The use of in vitro and in vivo disease models was essential to demonstrate the protective...