Metastatic cancer is a disease caused by mutation in cell’s DNA which causes cells to behave abnormally. These cells proliferate, migrate, and have an increased resistance to apoptosis. In our model, we will be focusing on the metastatic cancers affecting the mammary gland in female patients. Mammary glands form acini structures composed of epithelial cells in which fluids such as milk or blood flow through. The environment around epithelial cells can affect their mechanical behavior through chemical signaling and possibly lead cells through epithelial–mesenchymal transition (EMT). Initial stages of EMT are associated with destabilization of breast acini structure. Using computer simulation, we aim to understand how variations in ECM stiffness and dynamic changes in cell mechanical properties due to chemical signaling affect the stability of acini structures.