In this study, Smad2 was highly expressed in bladder cancer tissue, which may be due to abnormal Smad2 signalling function during carcinogenesis, thus decreasing the inhibitory effects of the TGF‐β1/Smad pathway on cancer cells, enhancing the feedback signals from TGF‐β1 and increasing the expression of Smad2. Here, TGFB1 is linked to urinary bladder carcinoma.