Thus, let-7a-containing GE11-positive exosome can specifically bind to HCC70 breast cancer cells in RAG2–/– mice after intravenous injection, and the tumor growth was remarkably suppressed in vivo, which also implied that efficient tumor therapy can be achieved by GE11-positive exosomes through delivering miRNA to EGFR-expressing cancerous tissues. The gene discussed is EGFR; the disease is breast carcinoma.