Further studies showed that the tumor volume and weight in the GAS5 siRNA group were significantly higher than those in the NC group, whereas the tumor volume and weight in the GAS5 siRNA + miR‐21 group were significantly lower than those in the GAS5 siRNA group and NC group (Figure 9A‐C), meaning that low expression of miR‐21 could inhibit the growth of bladder cancer by upregulating the expression level of PTEN, and such a process was regulated by GAS5. The gene discussed is GAS5; the disease is urinary bladder cancer.