PP121 is a potent dual inhibitor targeting both PI3K and mTOR signaling pathways, making it valuable in cancer research. It is widely used in preclinical studies to investigate tumor growth suppression, particularly in cancers driven by dysregulation of the PI3K/AKT/mTOR pathway. Its ability to cross the blood-brain barrier enhances its utility in studying brain tumors and central nervous system malignancies. PP121 induces apoptosis and inhibits proliferation in various cancer cell lines, including lung, breast, and leukemia models. Researchers also use it to overcome resistance to other kinase inhibitors, due to its broad-spectrum kinase inhibition profile. Its application extends to studying angiogenesis and metastasis, supporting the development of new anticancer therapies.