NTAL: ProductsNon-T cell activation linker (NTAL), also known as linker for activation of B cells (LAB), is a transmembrane adaptor protein involved in immunoreceptor signaling. NTAL is expressed in lipid raft microdomains of B cells, mast cells, monocytes and NK cells. Rapid tyrosine phosphorylation of NTAL occurs upon BCR aggregation in B cells, Fc epsilon RI aggregation and Kit activation in mast cells, and Fc gamma RI aggregation in monocytes. Phosphorylated NTAL recruits signaling molecules such as Grb2, Gab1, and c-Cbl into receptor-signaling complexes. Defects in the NTAL gene may cause Williams-Beuren syndrome, a rare genetic disorder characterized by mild mental retardation, and abnormalities in the cardiovascular and musculo-skeletal systems.