Objective: The aim of our study was to investigate the effect of Cinobufacini injection on the proliferation and cell cycle of human hepatoma HepG-2 cells. Methods: Cell proliferation was assessed by MTT assay, cell cycle distribution was detected by the flow cytometry (FCM). The expression of Cyclin A, CDK2 mRNA levels were examined by RT-PCR. Quantitative colorimetric assay was used to analyze Cyclin A/CDK2 activity in HepG-2 cells. Results: Cinobufacini injection significantly inhibited HepG-2 cells proliferation in dose- and time-dependent ways; FCM analysis showed Cinobufacini injection induced cell cycle arrest at S phase; RT-PCR assay showed Cinobufacini injection down-regulated Cyclin A, CDK2 expression at mRNA levels; Quantitative colorimetric assay showed Cinobufacini injection deceased Cyclin A/CDK2 activity in HepG-2 cells. Conclusion: Cinobufacini injection can inhibit human hepatoma HepG-2 cells growth, induce cell apoptosis and induce cell cycle arrest at S phase, the mechanism of which might be partly related to the down-regulation of Cyclin A, CDK2 mRNA expression and inhibition of Cyclin A/CDK2 activity.Objective: The aim of our study was to investigate the effect of Cinobufacini injection on the proliferation and cell cycle of human hepatoma HepG-2 cells. Methods: Cell proliferation was assessed by MTT assay, cell cycle distribution was detected by the flow cytometry (FCM). The expression of Cyclin A, CDK2 mRNA levels were examined by RT-PCR. Quantitative colorimetric assay was used to analyze Cyclin A/CDK2 activity in HepG-2 cells. Results: Cinobufacini injection significantly inhibited HepG-2 cells proliferation in dose- and time-dependent ways; FCM analysis showed Cinobufacini injection induced cell cycle arrest at S phase; RT-PCR assay showed Cinobufacini injection down-regulated Cyclin A, CDK2 expression at mRNA levels; Quantitative colorimetric assay showed Cinobufacini injection deceased Cyclin A/CDK2 activity in HepG-2 cells. Conclusion: Cinobufacini injection can inhibit human hepatoma HepG-2 cells growth, induce cell apoptosis and induce cell cycle arrest at S phase, the mechanism of which might be partly related to the down-regulation of Cyclin A, CDK2 mRNA expression and inhibition of Cyclin A/CDK2 activity. Objective: The aim of our study was to investigate the effect of Cinobufacini injection on the proliferation and cell cycle of human hepatoma HepG-2 cells. Methods: Cell proliferation was assessed by MTT assay, cell cycle distribution was detected by the flow cytometry (FCM Quantitative colorimetric assay was used to analyze Cyclin A / CDK2 activity in HepG-2 cells. Results: Cinobufacini injection significantly inhibited HepG-2 cells proliferation in dose- and time-dependent ways; FCM analysis showed Cinobufacini injection induced cell cycle arrest at S phase; RT-PCR assay showed Cinobufacini injection down-regulated Cyclin A, CDK2 expression at mRNA levels; Quantitative colorimetric assay showed Cinobufacini injection deceased Cyclin A / CDK2 activity in HepG-2 cells. Conclusion: Cinobufacini injection can inhibit human hepatoma HepG-2 cells growth, induce cell apoptosis and induce cell cycle arrest at S phase, the me chanism of which might be partially related to the down-regulation of cyclin A, CDK2 mRNA expression and inhibition of Cyclin A / CDK2 activity. Objective: The aim of our study was to investigate the effect of Cinobufacini injection on the proliferation and Cell cycle of human hepatoma HepG-2 cells. Methods: Cell proliferation was assessed by MTT assay, cell cycle distribution was detected by the flow cytometry (FCM). The expression of Cyclin A, CDK2 mRNA levels were examined by RT-PCR. colorimetric assay was used to analyze Cyclin A / CDK2 activity in HepG-2 cells. Results: Cinobufacini injection significantly inhibited HepG-2 cells proliferation in dose- and time-dependent ways; FCM analysis showed Cinobufacini injection induced cell cycle arrest at S phase; RT-PCR assay showed Cinobufacini injection down-regulated Cyclin A, CDK2 expression at mRNA levels; Quantitative colorimetric assay showed Cinobufacini injection deceased Cyclin A / CDK2 activity in HepG-2 cells. Conclusion: Cinobufacini injection can inhibit human hepatoma HepG-2 cell growth, induce cell apoptosis and induce cell cycle arrest at S phase, the mechanism of which might be partially related to the down-regulation of Cyclin A, CDK2 mRNA expression and inhibition of Cyclin A / CDK2 activity.