Colony stimulating factor 1 receptor is a cell-surface protein encoded, in humans, by the CSF1R gene. It is a receptor for a cytokine called colony stimulating factor 1.The protein encoded by the CSFR1 gene 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 CSFR1 through a process of oligomerization and transphosphorylation. The encoded protein is a tyrosine kinase transmembrane receptor and member of the CSF1/PDGF receptor family of tyrosine-protein kinases. The first intron of the CSFR1 gene contains a transcriptionally inactive ribosomal protein L7 processed pseudogene, oriented in the opposite direction to the CSFR1 gene.