This protein tyrosine kinase transmembrane receptor is the receptor for colony stimulating factor 1, a cytokine which controls the production, differentiation, and function of macrophages. This receptor mediates most if not all of the biological effects of this cytokine. Ligand binding activates the receptor kinase through a process of oligomerization and transphosphorylation. The encoded protein is a member of the CSF1/PDGF receptor family of tyrosine protein kinases and contains 5 immunoglobulin like C2 type domains. CD115 is expressed by cells of the monocytic lineage and by progenitor cells. Mutations in this gene have been associated with a predisposition to myeloid malignancy.