Erythropoietin treatment alters other aspects of the EPAS1^–/– phenotype. Giemsa staining of bone marrow from representative (A) untreated (-Epo) EPAS1^–/– (–/–), (B) erythropoietin-treated (+Epo) EPAS1^–/– (–/–), or (C) EPAS1^+/+ (+/+) mice (all images are ×20 fields, equivalent size). The black bar in panel C corresponds to 100 μm. Representative oil red O (ORO) staining of liver from (D) untreated (-Epo) EPAS1^–/– (–/–), (E) erythropoietin-treated (+Epo) EPAS1^–/– (–/–), or (F) EPAS1^+/+ (+/+) mice (all images are ×20 fields, equivalent size). The black bar in panel F corresponds to 100 μm.