Expression profile of RUNX1, GATA-1, and CBFβ in healthy human bone marrow. Left panel, RUNX1; middle panel, GATA-1; right panel, CBFβ. Black arrows indicate megakaryocytes, and red arrows indicate erythroblasts. Immunoperoxidase staining was performed using avidin-biotin complex on paraffin-embedded marrow clot section. Slides were counterstained with Harris hematoxylin (original magnification, × 400).