GMCSF is a cytokine that controls the production, differentiation, and function of granulocytes and macrophages. The active form of the protein is found extracellularly as a homodimer. This gene has been localized to a cluster of related genes at chromosome region 5q31, which is known to be associated with interstitial deletions in the 5q- syndrome and acute myelogenous leukemia. Other genes in the cluster include those encoding interleukins 4, 5, and 13.GM-CSF stimulates the growth and differentiation of hematopoietic precursor cells from various lineages, including granulocytes, macrophages, eosinophils and erythrocytes. Granulocyte Macrophage Colony Stimulating Factor is a potent species-specific growth factor produced by a variety of cell types including T cells, B cells, macrophages, mast cells and endothelial cells. GM-CSF is produced in response to cytokine or immune stimulation and has been shown to stimulate the proliferation, maturation and function of hematopoietic cells Synonyms: CSF-2, MGI-1GM, GM-CSF, Pluripoietin-alpha, Molgramostin, Sargramostim, MGC131935, MGC138897