Granulocyte colony stimulating factor (G-CSF) is a glycoprotein that stimulates the production of granulocytes and stem cells in the bone marrow and releases them into the bloodstream. Functionally, it is a cytokine and hormone, a colony stimulating factor produced by endothelial cells, macrophages, and many other immune cells. G-CSF stimulates the survival, proliferation, differentiation, and functional development of neutrophil precursors and mature neutrophils. In oncology and hematology, recombinant G-CSF is used to accelerate the recovery of neutropenia caused by chemotherapy in cancer patients. Before removing white blood cells, G-CSF can also be used to increase the number of hematopoietic stem cells in the blood of blood donors for hematopoietic stem cell transplantation.