Objective:To investigate the mechanism of N-methyl-N-nitrosourea(MNU) derived bladder cancer.Methods:60 SD Rats were devided into experimental group and control group at random.NMU was used to intravesical perfuse per 2 weeks at the dose of 2 mg for 8 w in experimental group

while saline was used in control group.All rats was sacrificed to get the bladder at the end of 8 w.All bladders were stored in negative 80℃ liquid nitrogen.Ras was detected by immunohistochemistry

and PLCε mRNA was detected by RT-PCR.Results:Tumor appeared in 36 rats out of 50 rats in experimental group. Totally tumor formation rate was 81.82%.While there is no tumor appeared in control group.Ras protein was positive in 32 rats in experimental group by immunohistochemistry

while negative in control group. PCR showed PLCε mRNA was positive in experimental group

while negative in control group.Conclusion:MNU could induce the oncogenesis in bladder.The possible mechanism was MNU make Ras actived and PLCε overexpressed.