The high expression of MMP-9 can promote the metastasis of bladder cancer has been confirmed, and there is evidence that the process is associated with MMP-9 promoted epithelial-mesenchymal transition (EMT) in bladder cancer (Ashrafizadeh et al., 2020a; Mirzaei et al., 2021a; Mirzaei et al., 2021b). The gene discussed is MMP9; the disease is urinary bladder carcinoma.