Research has shown that exosomal miR-100-5p targets mTOR, enhancing its expression and consequently augmenting the resistance of tumor cells to chemotherapy.[51] Exosomes derived from cancer stem cells carry miR-210, which, when transferred to pancreatic cancer cells, activates the PI3K–AKT–mTOR signaling pathway and induces resistance to gemcitabine.[52] Tumor-associated macrophages release exosomes containing miR-21, which are delivered to gastric cancer cells. The gene discussed is AKT1; the disease is gastric cancer.