MERTK, also known as MER proto-oncogene tyrosine kinase, is a receptor tyrosine kinase and a member of the TAM (TYRO3, AXL, MERTK) family. It plays crucial roles in various physiological processes, including cell survival, migration, differentiation, and the phagocytosis of apoptotic cells, a process known as efferocytosis. MERTK is expressed in multiple tissues, such as macrophages and retinal pigment epithelial cells, and is involved in regulating immune responses and maintaining tissue homeostasis. In the immune system, MERTK helps macrophages clear apoptotic cells and inhibits the innate immune response by activating STAT1, which induces the production of suppressors of cytokine signaling (SOCS1 and SOCS3). Abnormal expression of MERTK has been linked to several diseases, including retinitis pigmentosa and certain cancers, making it a potential therapeutic target in cancer treatment.