Hemangioblasts are precursor cells that have the ability to differentiate into either haematopoietic or endothelial cells. However, the precise molecular events that give rise to these lineages and to the hemangioblast itself remain unclear. To determine the molecular signature of the hemangioblast and to identify factors that direct these cells to differentiate, Lugus et al. compared the gene expression profiles of embryonic stem cell-derived hemangioblasts to their differentiated progeny. On p. 393, the authors reveal how Gata2 transcripts are enriched in the hemangioblast cell population in comparison with other stem cell populations, and how GATA2 forms part of a positive feedback loop with BMP4. They further reveal how enforced early GATA2 expression in hemangioblasts leads to increased numbers of erythroid and endothelial progeny. Later expression leads to the development of larger erythroid colonies, which occurs independently of the hemangioblast. Whether GATA2 has further cell-type-specific roles in other developmental processes remains to be determined.