GRB14 is an adapter protein that modulates insulin receptor signaling through multiple molecular mechanisms. As a member of the Grb7/10/14 family, GRB14 contains conserved domains including an N-terminal proline-rich region, central pleckstrin homology domain, and C-terminal SH2 domain that enable protein-protein interactions 1. GRB14 acts as a potent inhibitor of insulin signaling by binding to the activated insulin receptor through its SH2 and PIR domains, thereby suppressing insulin receptor tyrosine kinase activity and downstream MAPK3 phosphorylation 2. Paradoxically, GRB14 also serves as an adapter to recruit PDPK1 to the insulin receptor, promoting PKB/AKT1 phosphorylation 3. Mouse knockout studies demonstrate that GRB14 ablation enhances insulin action in liver and skeletal muscle, improving whole-body glucose tolerance 3. GRB14 expression is high in metabolic tissues including liver, kidney, pancreas, and skeletal muscle 1. Clinically, GRB14 variants associate with nonalcoholic fatty liver disease susceptibility 4, lipedema phenotypes 5, and Alzheimer's disease in Hispanic populations 6. Pharmacological inhibition of GRB14 may enhance insulin sensitivity in insulin-resistant states 7, suggesting therapeutic potential for metabolic disorders.