Csf2 is the gene that encodes GM-CSF (granulocyte-macrophage colony stimulating factor), which is conserved in human, chimpanzee, Rhesus monkey, dog, cow, mouse, and rat. GM-CSF plays a key role in signaling emergency hemopoiesis (predominantly myelopoiesis) in response to infection, including the production of granulocytes and macrophages in the bone marrow and their maintenance, survival, and functional activation at sites of injury or insult. The receptor for GM-CSF is a heterodimer that comprises a major binding subunit (GMRalpha) and a major signaling subunit (beta-c). The beta-c chain is a common subunit for GM-CSF, IL-3, and IL-5 receptors. The receptor subunits are always coexpressed on the surface of leukocytes, with beta-c being expressed at lower levels than GMRalpha. Certain nonhemopoietic cell types also express the GM-CSF receptor. GM-CSF has anti-apoptotic functions on neurons and is neuroprotective in animal stroke models. It stimulates neuronal differentiation of adult neuronal stem cells (NSCs). GM-CSF has been identified as a factor involved in arteriogenesis after brain ischemia. In addition, GM-CSF induces arteriogenic growth of collateral vessels after occlusion of cardiac or peripheral arteries.?