Moreover, Bcl2 and Bcl-XL, as pro-survival genes directly transcripted by STAT3 [11], were also repressed by metformin, suggesting that down-regulaiton of STAT3/Bcl2/Bcl-XL signaling pathways in metformin-treated bladder cancer cells caused increased apoptotic cell death. This evidence concerns the gene BCL2 and urinary bladder carcinoma.