Fig. 1. GATA2 expression is turned on in newborn progenitors and is sufficient to arrest proliferation. (A) Transverse section of the caudal hindbrain of a E10.5 mouse embryo, first hybridised with Gata2 anti-sense RNA (green), then stained with antibodies against Isl1 (red), a pan-marker of motoneurons. The presumptive domain of V2 precursors, which express Gata2, is located between the respective domains of the motoneuron and V1 interneuron precursors; in the hindbrain, Gata2 is also activated to a lesser extent in the p3 domain, indicated by the white arrow. (B,C) Transverse section of the spinal cord of a E10.5 mouse embryo injected with BrdU. Hybridisation with Gata2 antisense RNA (B) was followed by BrdU immunostaining (C). (D-F) Higher magnification of the area included in the white rectangle in C. (G-L) Transverse sections of the spinal cord of chick embryos 24 hours after electroporation with the pAdRSV-GATA2HA plasmid, double-stained with anti-HA antibodies (G,J) and either with anti-phospho-Histone3 (pH3) (H) or anti-BrdU antibodies (K), and analysed by confocal microscopy. (I,L) Superimpositions of G,H (I) and J,K (L). (M,N) The percentages of phospho-Histone3- and BrdU-positive cells in the control (red, M) and the transfected sides (blue, N) are compared. (O,P) Adjacent sections of chick embryos misexpressing GATA2-HA, stained with anti-HA-antibodies and hybridised with chick Sox2 anti-sense RNA. Scale bar: in A, 70 µm in A-C; in D, 20 µm in D-F; in G, 20 µm in G-L; in O, 50 µm in O,P.