P21926

CD9 also known as Tetraspanin-29, MRP-1 is a type IV transmembrane glycoprotein with four transmembrane domains and is widely expressed on the surface of various cell types, including early B cells, eosinophils, basophils, activated T cells, and platelets. CD9 is integral to cell-cell adhesion, particularly during immune responses and cellular communication. Additionally, CD9 plays a significant role in signal transduction, interacting with low molecular weight GTP-binding proteins to influence intracellular signaling pathways. CD9 is also implicated in the regulation of cell migration, adhesion, and fusion, processes that are critical in immune function, tissue repair, and development. CD9 is associated with a range of pathological conditions and is expressed on non-T acute lymphoblastic leukemia cells and some acute myeloid and chronic lymphoid leukemias, highlighting CD9′s importance as a marker for certain hematological malignancies. As a major component of the platelet surface, CD9 is essential in platelet aggregation and clot formation.