CFU-GEMM  CFU-GEMM is a colony forming unit that generates myeloid cells. CFU-GEMM cells are the oligopotential progenitor cells for myeloid cells; they are thus also called common myeloid progenitor cells or myeloid stem cells. "GEMM" stands for granulocyte, erythrocyte, monocyte, megakaryocyte. The common myeloid progenitor (CMP) and the common lymphoid progenitor (CLP) are the first branch of cell differentiation in hematopoiesis after the hemocytoblast (hematopoietic stem cell). In current terminology, CFU-S refers to the pluripotent stem cells that can differentiate into all types of blood cells. CFU-S divides into two lineages: the lymphoid precursor (CFU-LSC) and the myeloid precursor (CFU-GEMM). The CFU-GEMM cell is capable of differentiating into white blood cells, red blood cells, and platelets, all of which are normally found in circulating blood. It has been suggested that eosinophils do not derive from the common myeloid progenitor in humans. In the adjacent image, CFU-GEMM is the scientific name for the "common myeloid progenitor" that is responsible for forming all the cells of the myeloid lineages. As observed in the image, CFU-GEMM is capable of producing a diverse set of cells. It matures into the megakaryocyte, erythrocyte, mast cell or myeloblast based on the presence of specific factors that encourage the cell to choose a lineage to follow. The cells are characterized by expressing the cell surface markers CD33, CD34 and HLA-DR. These surface markers are proteins on the surface that are unique to specific cells and certain maturation periods, allowing researchers to differentiate between two different cells as well as what stage the cell is found in its developmental progression. The differentiation and proliferation of CFU-GEMM are promoted by growth factors, such as interleukins and cytokines. IL-3 and GM-CSF as single factors are equally active in stimulating CFU-GEMM, but the combination of both factors produces additive stimulatory effects upon CFU-GEMM. The growth of CFU-GEMM is stimulated by the stem cell factor, or SCF.