MTOR and central nervous system cancer: (84) used metformin and combined drugs to intervene in GBM glioma stem cells, and observed that metformin may inhibit the specific phosphorylation of mTOR and Signal Transducer and Activator of Transcription 3(STAT3) by activating AMPK, and metformin and statins also reduced the total STAT3 level at high doses.