Fax: + 1 615 343 4589.Abbreviations. BFU-E, burst-forming-unit erythroid; CFU-E, colony-forming-unit erythroid; CHO, Chinese hamster ovary; EPO, erythropoietin; FVA cells, splenic erythroblasts from mice infected with Friend leukemia virus (anemia-inducing strain); GATA-I, transcription factor that binds DNA sequence GATA in erythroid cells; GM-CSF, granulocyte-macrophage colony-stimulating factor; HCD cells, an erythropoietin-dependent murine erythroleukemia cell line; rh-EPO, recombinant human erythropoietin; SFFVp, Friend spleen focus-forming virus (polycythemia-inducing); uh-EPO, urinary human erythropoietin; IL, interleukin.