Loss of E-cadherin function or expression has been implicated in cancer progression and metastasis. E-cadherin downregulation decreases the strength of cellular adhesion within a tissue, resulting in an increase in cellular motility. This in turn may allow cancer cells to cross the basement membrane and invade surrounding tissues. E-cadherin is also used by pathologists to diagnose different kinds of breast cancer. When compared with invasive ductal carcinoma, E-cadherin expression is markedly reduced or absent in the great majority of invasive lobular carcinomas when studied by immunohistochemistry. CDH1 (gene) has been shown to interact with    Transitions between epithelial and mesenchymal states play important roles in embryonic development and cancer metastasis. E-cadherin level changes in EMT (epithelial-mesenchymal transition) and MET (mesenchymal-epithelial transition). E-cadherin acts as an invasion suppressor and a classical tumor suppressor gene in pre-invasive lobular breast carcinoma. E-cadherin is a crucial type of cell-cell adhesion to hold the epithelial cells tight together. E-cadherin can sequester β-catenin on the cell membrane by the cytoplasmic tail of E-cadherin. Loss of E-cadherin expression results in releasing β-catenin into the cytoplasm. Liberated β-catenin molecules may migrate into the nucleus and trigger the expression of EMT-inducing transcription factors. Together with other mechanisms, such as constitutive RTK activation, E-cadherin loss can lead cancer cells to the mesenchymal state and undergo metastasis. E-cadherin is an important switch in EMT. The mesenchymal state cancer cells migrate to new sites and may undergo METs in certain favorable microenvironment. For example, the cancer cells can recognize differentiated epithelial cell features in the new sites and upregulate E-cadherin expression. Those cancer cells can form cell-cell adhesions again and return to an epithelial state. Several proteins such as SNAI1/SNAIL, ZFHX1B/SIP1, SNAI2/SLUG, TWIST1 and DeltaEF1 have been found to downregulate E-cadherin expression.