In the present study, we generated protein-based PLC-γ1 inhibitors consisting of PLC-γ1-SH2 domains fused to the TAT leader sequence as highly specific inhibitors to block PLC-γ1 tyrosine phosphorylation, thereby inhibiting the EGF-induced migration of EGFR/c-erbB-2-positive breast cancer cells. The gene discussed is EGFR; the disease is breast cancer.