The JAK (Janus kinase) family comprises four enzymes: JAK1, JAK2, JAK3, and Tyk2. They are a class of membrane-associated tyrosine kinases primarily located in the cytoplasm. By mediating the response of cell surface receptors to cytokines and growth factors, they activate STAT proteins, participating in various signaling pathways, including immune regulation, cell proliferation, differentiation, and apoptosis. The expression of JAK family members is cell-type and tissue-specific, and mutations or aberrant activation are closely associated with the development of various diseases such as myeloproliferative disorders, autoimmune diseases, and certain cancers.