Objective:To investigate the effect of actin phosphorylation on the migration ability in human breast(MDA-MB-231)cancer cells and its role in the reorganization of actin cytoskeleton. Methods:The MDA-MB-231 cells were treated with LPA(10 μmol/L)for 4 h. Migration rate was measured by Transwell assay. The contents of G-actin(in cytosolic fraction) and F-actin(in cytoskeletal fraction) in cells were evaluated by Western blotting. Two-dimensional electrophoresis was used to separate phosphorylated actin from unphosphorylated actin in cytosolic and cytoskeletal fraction of cells. Results:After treated with LPA for 4h,the ability of migration in MDA-MB-231 cells was significantly increased compared to the control cells. Consistently,the cellular F-actin was also polymerized after LPA treatment. The proportion of phoshprylated actin after LPA treatment was higher than that of control cells. The further study demonstrated that dephosphorylated actin was only found in cytoplasmic fraction rather than in cytoskletonal fraction. Conclusion:LPA can enhance the ability of migration and polymerization of actin cytoskeleton in MDA-MB-231 cells probably through the phosphorylation of actin.