Cytokine that plays an essential role in the regulation of survival, proliferation and differentiation of hematopoietic precursor cells, especially mononuclear phagocytes, such as macrophages and monocytes. Promotes the release of pro-inflammatory chemokines, and thereby plays an important role in innate immunity and in inflammatory processes. Plays an important role in the regulation of osteoclast proliferation and differentiation, the regulation of bone resorption, and is required for normal bone development. Required for normal male and female fertility. Promotes reorganization of the actin cytoskeleton, regulates formation of membrane ruffles, cell adhesion and cell migration. Plays a role in lipoprotein clearance. Homodimer or heterodimer; disulfide-linked. Interacts with CSF1R. N-glycosylated. The predominant soluble form is a chondroitin sulfate-containing proteoglycan. A defect in Csf1 is the cause of osteopetrosis. Osteopetrotic mice (op/op) are severely deficient in mature macrophages and osteoclasts, display failed tooth eruption, and have a restricted capacity for bone remodeling. The sequence reported in PubMed:8357831 was thought to originate from rat, but was later shown (PubMed:12074592 and PubMed:12379742) to be derived from mouse.