Representative images of GATA1 immunoexpression in bone marrow biopsy samples according to the intensity of the reaction (×400): (A) negative, (B) weak, (C) moderate, and (D) strong. Megakaryocytes (arrows) are identified by CD61-stained (pink-colored) cytoplasm. GATA1-stained nuclei of megakaryocytes colored light to dark brown depending on the immunointensity. GATA1-stained nuclei are also seen in erythroid cells (arrowhead) without the CD61-positive cytoplasm.