Results of 3H-thymidine incorporation assays, Matrigel invasion assays, and xenografts in mice showed that mock-transfected bladder carcinoma cells grew slower in vitro and in vivo than the MT3-overexpressed bladder carcinoma cells, whereas MT3-knockdown attenuated cell invasion of TSGH-8301 cells. The gene discussed is MT3; the disease is urinary bladder carcinoma.