Abstract: It is studied that induction of apoptosis by TPA and its relationship with TR3 and RXRα in hepatocellular cell SMMC7721.Hepatocellular cell line,SMMC7721 was used in the experiments.Growth suppression was detected with MTT colorimetric assay.Apoptotic morphology was observed by DAPI fluorescence staining,and apoptotic index was counted among 1?000 cells randomly.Inhibition of RXRα transcriptional activity by TPA was detected by CAT assay.The expression level of RXRα protein was detected by Western Blot.The expression level of TR3 mRNA was detected by RT-PCR.Growth suppression was observed with MTT colorimetric assay.The inhibitory effect was dose-dependent.Treatment of SMMC7721 cells with TPA resulted in apoptosis,accompanied by the repression of RXRα protein in a time-dependent manner.At the same time,TPA also up-regulated expression level of TR3 mRNA in SMMC7721 cells that expressed TR3 mRNA.Inhibition of RXRα transcriptional activity by TPA was observed by CAT assay.TPA inhibits proliferation,induces apoptosis of SMMC7721 cells.Expression level of TR3 mRNA in SMMC7721 was induced by TPA.TPA repressed expression level of RXRα protein and inhibited RXRα transcriptional activity.And apoptosis has some relation with TR3 and RXRα.