A role for Grb2 in apoptosis?

Src homology type 2 (SH2) and type 3 (SH3) domains appear to have an important role in signal transduction pathways initiated by tyrosine kinases. SH2 domains allow proteins with signalling functions to interact with tyrosine kinases and tyrosine-phosphorylated proteins at the plasma membrane, whereas SH3 domains allow a distinct type of interaction through binding to proline-rich sequences. The adaptor protein Grb2 consists of one SH2 domain and two SH3 domains and connects tyrosine kinase receptors to activation of the Ras pathway.