Recombinant mouse GM-CSF can regulate growth and differentiation of cells of the myeloid lineage such as DCs, granulocytes, monocytes, and macrophages. As a crucial part of the immune/inflammatory path, the hematopoietic cytokine serves as both an activation signal for mature myeloid cells and survival. The recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) is developed for use in functional assays, differentiation studies, and cell culture.