GRB2 also known as ASH binds the epidermal growth factor receptor and contains one SH2 domain and two SH3 domains. GRB2 plays a crucial role in cellular signaling pathways, particularly in the regulation of growth factor receptor signaling, which is essential for normal cellular functions such as proliferation, differentiation, and survival. GRB2 acts as an adaptor that links activated receptor tyrosine kinases, like the epidermal growth factor receptor (EGFR), to downstream signaling molecules, thereby facilitating the activation of Ras and other pathways involved in cell growth and development. GRB2′s importance is underscored by its involvement in embryogenesis, where GRB2 is necessary for the differentiation of endodermal cells and the formation of the epiblast, highlighting its critical role in early developmental processes.