Objective:To investigate the effects of genestin on the actin cytoskeleton and its mechanisms involeved in p38 kinase-HSP27 signaling pathway. Methods:The breast cancer cells(MDA-MB-435 cells) were treated with different concentrations of genistein(12.5,25.0,50.0 and 100.0 -滋mol/L) for 24 h. The expressions of p38 kinase and HSP27 and the phosphorylation of p38 and HSP27 were evaluated by Western blotting analysis. The expressions of actin and HSP27 in cytosolic fraction and cytoskeletal fraction were also detected by Western blotting. Results:After treated with genistein for 24 h,cellular F-actin was depolymerized and the phosphorylation of p38 kinase and HSP27 was significantly attenuated compared with the control cells. HSP27 translocated from the cytosolic fraction to the cytoskeletal fraction simultaneously. Conclusion:These findings suggested that the reorganization of actin cytoskeleton induced by genistein should probably be mediated by translocation of HSP27 in cells via p38 kinase signaling pathway.