PT-88, a highly selective mTOR (Mammalian target of rapamycin) inhibitor (IC 50 =1.2 nM), effectively targets both mTORC1 and mTORC2 complexes. These complexes represent the active isoforms of mTOR protein kinases, integral to cell growth, proliferation, and survival. The utility of PT-88 extends to researching mTOR's involvement in tumorigenesis and development, with significant applications in breast cancer treatments.