Essential enhancers governing Gata2 expression and hematopoiesis. (A) The −77 and +9.5 enhancers reside 77 and 9.5 kb upstream and downstream, respectively, of the Gata2 transcriptional start site. These evolutionarily conserved enhancers control mouse and human Gata2 transcription in specific biological contexts and vital steps in hematopoiesis (depicted with brackets). (B) The photomicrographs depict Giemsa-stained myeloerythroid progeny resulting from ex vivo differentiation of −77^+/+ or −77^−/− fetal liver progenitor cells. AGM, aorta gonad mesonephros region of the embryo proper.