TGF-β signaling is well-known for its involvement in cancer invasion11, to examine the role of TGF-β pathway in bladder cancer invasion in vivo, we crossed Tgfbr2 flox mice with K5Cre-ER mice, and tamoxifen was applied to tumor-bearing mice after 26 week of BBN treatment. Here, TGFB1 is linked to urinary bladder cancer.