Granulocyte colony-stimulating factor (G-CSF) is a growth factor and cytokine belonging to the IL-6 family of interleukins. It is produced by a variety of cells such as: endothelial cells, bone marrow stroma, macrophages, fibroblasts, and other immune cells in response to endotoxin activation. G-CSF stimulates the bone marrow to stimulate the survival, proliferation and differentiation of progenitor cells to mature neutrophils while enhancing its activities. It indirectly mobilizes stem cells by downregulating the expression of CXCL12 on marrow osteoblasts and releases neutrophil and monocyte proteolytic enzymes. Mouse G-CSF affects mouse skeletal muscle development by activating proliferation of myoblasts. Human and murine G-CSF shares a 73% amino acid identity and is cross-reactive.