CDH1, also known as E-cadherin and CD324, is a calcium-dependent cell adhesion molecule. It consists of five extracellular domains with repeated cadherin motifs, a transmembrane domain, and an intracellular domain that can bind to p120-catenin and β-catenin. In adult tissues, CDH1 is expressed in epithelial tissues where it undergoes continuous regeneration, and its half-life on the cell surface is about 5 hours. Dysfunction or loss of CDH1 function and expression is associated with tumor progression and metastasis. Downregulation of CDH1 expression reduces cell adhesion strength within tissues, leading to increased cell motility. Conversely, it allows cancer cells to penetrate the basement membrane and invade surrounding tissues. Pathologists often use CDH1 for diagnosing different types of breast cancer. Immunohistochemical studies have shown significantly reduced or mostly absent expression of CDH1 in invasive lobular carcinoma compared to invasive ductal carcinoma.