Studies have shown that miR‐21 is associated with prognosis of colorectal cancer, esophageal cancer, and hepatocellular carcinoma.15, 16, 17 Recent study has also shown that miR‐21 participates in the development and progression of bladder cancer through transforming growth factor‐beta variants or PPP2R2A/ERK.18 In recent years, study has found that GAS5 can inhibit metastasis of liver cancer cells by inhibiting miR21 in hepatocellular carcinoma.19 This evidence concerns the gene GAS5 and urinary bladder carcinoma.