Abstract: Objectives : To transfect a bladder cancer cell line with pcDNA3-UpIb-promoter-Smac, a eukaryotic expression vector carrying the UpIb promoter and the Smac gene and to study the effectiveness of its apoptosis-promoting capabilities. Methods : The bladder cancer cell line BIU-87 was transfected with plasmid by liposome. After 24 hours, the expression of Smac was detected by RT-PCR. Low-dose mitomycin C induced apoptosis which was detected by inverted microscopy with Wright-Giemsa staining, DNA agarose gel electrophoresis, TUNEL fluorescence-labeled technique and flow cytometry. Results : In all groups exposed to mitomycin C, typical morphological features of apoptosis could be detected by inverted microscopy with Wright-Giemsa staining, and DNA ladder could be detected by DNA agarose gel electrophoresis. The apoptosis rate of BIU-87 cells transfected with pcDNA3-UpIb- promoter-Smac was significantly higher than that of the control cells that were not transfected as detected by TUNEL fluorescence-labeled technique and flow cytometry. Conclusions : The transfection of BIU-87 cells with pcDNA3-UpIb-promoter-Smac increased the expression of Smac and effectively promoted the apoptosis of BIU-87 cells induced by mitomycin C. Cooperative application of this vector and apoptosis-inducing drugs provides a new option for targeted gene therapy of bladder cancer.