Colony stimulating factor 1 (CSF-1) is a homodimeric polypeptide growth factor whose primary function is to regulate the survival, proliferation, differentiation, and function of cells of the mononuclear phagocytic lineage. This lineage includes mononuclear phagocytic precursors, blood monocytes, tissue macrophages, osteoclasts, and microglia of the brain, all of which possess cell surface receptors for CSF-1. The protein has also been linked with male fertility [1] and mutations in the Csf-1 gene have been found to cause osteopetrosis and failure of tooth eruption [2]. Structurally these are short-chain 4-helical cytokines.

1: Colony-stimulating factor 1 regulation of neuroendocrine pathways that control gonadal function in mice. Cohen PE, Zhu L, Nishimura K, Pollard JW; Endocrinology 2002;143:1413-1422. PMID:11897698

2: The osteopetrotic mutation toothless (tl) is a loss-of-function frameshift mutation in the rat Csf1 gene: Evidence of a crucial role for CSF-1 in osteoclastogenesis and endochondral ossification. Van Wesenbeeck L, Odgren PR, MacKay CA, D'Angelo M, Safadi FF, Popoff SN, Van Hul W, Marks SC Jr; Proc Natl Acad Sci U S A 2002;99:14303-14308. PMID:12379742