GAB1 (GRB2-associated-binding protein 1) is a 110 kDa member of the GAB family of scaffolding proteins. It is widely expressed, including in T and B cells, and serves as an adaptor molecule for the transmission of signals from cytokine and growth factor receptors. Tyrosine phosphorylation of GAB1 by multiple receptor tyrosine kinases, such as HGF R/c-Met, mediates interaction with multiple proteins containing SH2 domains, such as SHP-2.