<p>Junctional Adhesion Molecule A (JAM-A) is a multifunctional cell surface protein, belonging to the immunoglobulin superfamily of cell adhesion receptors involved in tight-junction formation. The molecule regulates breast cancer growth and invasion, and influences intercellular interactions between leukocytes, platelets and endothelial or epithelial cells, which influence metastatic progression. The main aim of this review is to provide an overview of the functional role of JAM-A in breast cancer metastasis, including its molecular interactions, cellular functions and contribution to <i>inter alia</i> cell migration, cell adhesion, epithelial-to-mesenchymal transition, apoptosis and metastasis. However, the molecular mechanism and signaling pathways regulating JAM-A protein in breast cancer are still not fully defined and require further investigation. Nevertheless, JAM-A appears a promising target for future diagnostic applications and drug development in breast cancer.</p>