Purity >95% as determined by SDS-PAGE. Macrophage colony stimulating factor (M-CSF) is a hematopoietic growth factor that is widely produced by a variety of cells. M-CSF stimulates the proliferation and differentiation of hematopoietic stem cells into monocyte and macrophage cell types. M-CSF also acts through the colony stimulating factor 1 receptor (CSF1R) to modulate processes involved in immunology, bone metabolism, fertility, and pregnancy. Human M-CSF shows activity on mouse cells; however, mouse CSF shows no activity on human cells.