CSF1R, or Colony-Stimulating Factor 1 Receptor, also known as CD115 and M-CSF-R, is a transmembrane receptor that belongs to the type III protein tyrosine kinase receptor family. It is primarily expressed on monocytes/macrophages, peritoneal exudate cells, plasmacytoid and conventional dendritic cells, and osteoclasts. The natural ligands for CSF1R include CSF1 and IL-34, which directly affect the differentiation and proliferation of tissue macrophages and osteoclasts. CSF1R plays a role in various physiological processes, including regulating the proliferation of early hematopoietic progenitor cells and influencing many physiological processes involved in immunology, metabolism, fertility, and pregnancy. Additionally, CSF1R is involved in modulating the function of tumor-associated macrophages (TAMs), which can suppress tumor immunity. CSF1R also plays an important role in the central nervous system and neurological diseases.