tokens: Azidothymidine ( AZT )- induced anemia in mice can be reversed by the administration of IGF - IL - 3 ( fusion protein of insulin - like growth factor II ( IGF II ) and interleukin 3 ). Although interleukin 3 ( IL - 3 ) and erythropoietin ( EPO ) are known to act synergistically on hematopoietic cell proliferation in vitro , injection of IGF - IL - 3 and EPO in AZT - treated mice resulted in a reduction of red cells and an increase of plasma EPO levels as compared to animals treated with IGF - IL - 3 or EPO alone .