SOS1 and posterior cortical atrophy: Additionally, the SH2 domain involves the binding of GRB2 to receptor proteins, thereby recruiting GRB2 and SOS1 to the membrane and mediating signal transduction.[35] We stably knocking down GRB2 with transfecting PCa cells with a GRB2 mutant plasmid deficient in bases expressing the SH2 domain sequence (GRB2mut), and found that activation of the MAPK signaling pathway was abolished (Figure 4I).