NCK1 is one of the adaptor proteins which mediate specific protein-protein interactions in signaling processes. Adaptor proteins usually contain several domains like SH2 and SH3 which allow specific interactions with other specific proteins. NCK1 and NCK2 show high sequence identity (68%) and have three SH3 domains and a C-terminal SH2 domain. Both of them bind receptor tyrosine kinases such as PDGFR and other tyrosine phosphorylated proteins via their SH2 domains. Various molecules which interact with SH domains of Nck and regulate signaling process of actin cytoskeleton reorganization have been identified. Ncks are thought to have important functions in the development of mesodermal structures during embryogenesis, linked to a role in cell movement and cytoskeletal reorganization. Ncks also have a function in modulating mRNA translation at the level of initiation by interacting eukayotic initiation factor 2 (eIF2). Under stressed conditions, protein synthesis is reduced by inhibiting the activity of eIF2 through phosphorylation, transiently inhibiting recycling of eIF2 into its active form.