Similarly, the steroidal saponin C21 extracted from Marsdenia induces protective autophagy in GC cells by inhibiting the PI3K/AKT/mTOR signaling pathway, while activating the PTEN/AKT/mTOR signaling pathway to induce apoptosis of tumor cells (Li K. et al., 2020). The gene discussed is PIK3CA; the disease is gastric cancer.