Rho family proteins are small signaling G proteins which sense environmental properties and regulate actin reorganization and stress fiber. Rho family is known to be related to EMT process as cell transformation including loss of cell to cell junction mediated by E-Cadherin repression as cancer initiation process. In this research, we apply axial tensile stress to human mammary gland cell to study the possibility where tensile stimulus could induce EMT as cancer initiation factor. Upon the application of 10% strain at 0.5 Hz up to 12hours, normal breast cells (MCF10A) show significant changes in their MMP3, RhoA, Rac1, Rac1b and Cdc42 gene and protein expressions while E-Cadherin is suppressed. Changes of Rho family expression had been eliminated by suppressing ROCK which is Rho kinase. These results indicate that continuous mechanical stretching might lead normal breast cell to show EMT phenotypes through MMP-Rho-actin related pathway.