Involved in primitive hematopoiesis in the embryo. Heterodimer with cbfb. runx1 binds DNA as a monomer and through the Runt domain. DNA-binding is increased by heterodimerization (By similarity). Shows a complex and dynamic expression pattern. In stage 14-24 embryos, expressed in a subset of neuroblasts in the lateral stripe of the neural plate. In late neurula stages, expression begins in the olfactory placodes. Also expressed in structures that play a role in blood formation: at stage 14, expressed on the anterior ventral side of the embryo in the anterior endomesoderm. As the embryo elongates, expression shifts gradually to a V-shaped expression pattern in the presumptive ventral blood island. Expressed both maternally and zygotically. Shows a small amount of maternal expression. Zygotic expression begins at stage 8 and steadily increases after this point. By low levels of the dorsalizing factor LiCl. Inhibited by high doses of LiCl. In order to temporally control hematopoiesis, fgf-signaling inhibits expression in posterior regions of the embryo by antagonizing bmp-signaling.