Non-T cell Activation Linker (NTAL) is also known as linker for activation of B cells (LAB), is a transmembrane adaptor protein. NTAL is expressed in B cells, mast cells, monocytes and NK cells. When NTAL is tyrosine phosphorylated, it recruits signalling molecules such as Grb2, Gab2 and c-Cbl into receptor-signalling complexes. Mutation in the NTAL gene may cause Williams-Beuren syndrome, a rare genetic disorder.