particularly good indicator of the differential motility, proliferation, and invasiveness in the breast cancer cells. Cellular microenvironment is critical in the orchestration of tumorogenesis and metastasis. Various factors present in the microenvironment, such as growth factor concentrations, homing receptors, matrix components, and mechanical properties of the matrix, have been shown to affect tumor growth and metastasis. In this study, we focused on the effect of the mechanical rigidity of the ECM on proliferation and invasiveness of the breast cancer cells. Mechanosensing is involved in cell motility, matrix remodeling, and development, as well as in a number of pathological processes, such as tumor formation and metastasis. The rigidity of the extracellular matrix is one of the critical properties of the ECM and different cell types respond to matrix rigidity in fundamentally different ways. The specific matrix rigidity requirements in different cell types have been correlated with the rigidities of their native tissues in vivo. In addition, the differentiation of the stem cells through changes in gene expression was shown to depend on matrix rigidity. Application of external mechanical force enhances integrin clustering and the subsequent recruitment of focal contact proteins, that, in turn, associate with the actin cytoskeleton and activate multiple signaling proteins including focal adhesion kinase, Src family kinases, Rho GTPase, and integrin-linked kinase, to promote cell growth, migration, and differentiation. In addition to the overall rigidity response being altered in malignantly transformed cells in vitro, similar behavior was described in vivo further emphasizing the relevance of proper mechanosignaling to complex LBH-589 processes such as differentiation, development, migration, and regeneration. Interactions between epithelial cells and the extracellular matrix regulate mammary gland development, and are critical for the maintenance of tissue homeostasis. The extracellular matrix regulates growth, survival, migration, and differentiation through a variety of transmembrane receptors. Similar to breast development, malignant transformation of the breast is also NSC53909 associated with significant alterations