Model for the role of Gata1 in adult erythromegakaryopoiesis. Normal erythromegakaryopoiesis (top panel) and in the absence of Gata1 (bottom panel). Gata1 has a role in myeloid progenitors. Gata1 loss results in reduction of BFUe, CFUe, and defective erythroid differentiation beyond the proerythroblast stage. In megakaryocytes, Gata1 loss might be compensated by Gata2; however, Gata1 regulates megakaryocyte proliferation and is required for proper cytoplasmic maturation.³⁹  HSC indicates hematopoietic stem cell; PrE, proerythroblast; B, basophilic erythroblast; P, polychromatic erythroblast; O, orthochromatic erythroblast; Ery, mature erythrocyte.