Abstract: ObjectiveTo study the inhibitory action of paclitaxel liposome to breast cancer cell (MCF-7) and analyze the mechanism through detecting the time-concentration effect of paclitaxel liposome. Methods MCF-7 cells were cultured and treated with different concentration of paclitaxel liposome.The cell viability was analyzed by MTT.Cell morphology was observed inverted microscope.Cell apoptosis and cell cycle arrest status were detected by flow cytometry.The expressions of bcl-2 and bax proteins were detected by Western blot ResultsThe paclitaxel liposome could inhibit MCF-7 cells by time and concentration-dependent effect.The paclitaxel and paclitaxel liposome could block MCF-7 cells at G2/M phase,and cell apoptosis was more obvious along with drug concentration increasing.The Western blots results demonstrated that after using paclitaxel liposome,the expression of bcl-2 protein was obviously decreased,while the expression of bax protein increased.The value of bax/bcl-2 was up-regulated. Conclusion Compared with paclitaxel,paclitaxel liposome can similarly inhibit MCF-7 cells.One of the pro-apoptotic mechanisms is regulating the expression of bcl-2 and bax.