For example, it was demonstrated that exosomes specifically deliver miRNAs to epidermal growth factor receptor (EGFR)-expressing breast cancer cells using engineered donor cells expressing a transmembrane structural domain of the platelet-derived growth factor receptor fused to the GE11 peptide receptor, while the team also found that exosomes containing let-7a miRNA were expressed in EGFR-expressing xenograft breast cancer tissue when administered intravenously to RAG2(− / −) experimental mice [26]. This evidence concerns the gene EGFR and breast cancer.