MyD88 is an adapter protein, belonging to the MyD88 family of members. Its structure consists of the N-terminal TIR domain and the C-terminal DD domain. MyD88 is widely distributed in various cells and tissues, localized in the cytoplasm and cell membrane. It participates in regulating immune and inflammatory responses, serving as an important adapter protein for Toll-like receptor and IL-1 receptor signal transduction, activating NF-κB and MAPK signaling pathways. The gene expression of MyD88 is regulated by multiple factors, with its specific expression varying in different tissues and disease states. Although MyD88 mutations are not common, they have been associated with some immune-related diseases and cancer development, making research on its biological and clinical significance crucial.