First, it activates AMP-activated protein kinase (AMPK) to lower the blood glucose level, which can indirectly inhibit the growth of tumor cells.[29] Meanwhile the activation of AMPK also downregulates the mammalian target of rapamycin (mTOR), which eventually induces growth inhibition of cancer cells and protein synthesis arrest.[30] A study by Zhang et al[31] showed that metformin inhibits the growth of bladder cancer cells via indirect activation of AMPK, which in turn suppresses the mTOR/p70 S6 kinase-1 (S6K1) pathway in 253J and RT4 bladder cancer cell lines. Here, MTOR is linked to urinary bladder carcinoma.