ALCAM (activated leukocyte cell adhesion molecule) is a transmembrane immunoglobulin receptor mediating homophilic and heterophilic cell-cell adhesion with context-dependent functions across immune, neurological, and malignant processes 1. Structurally, ALCAM contains five immunoglobulin-like domains and undergoes proteolytic shedding via metalloproteases 2. Beyond canonical adhesion, ALCAM interacts with CD6 and EGFR to modulate signaling; notably, ALCAM-EGFR binding blocks EGF-induced Mek/Erk and PI3K/Akt pathways 3. In malignancy, ALCAM expression is tumor-type dependent: high expression correlates with poor prognosis in melanoma and serves as a cancer stem cell marker 12, yet ALCAM acts as a negative regulator of multiple myeloma clonogenicity and predicts improved survival 3. Beyond oncology, ALCAM mediates pathogenic CD4 Th17 cell adhesion to oligodendrocytes in multiple sclerosis 4 and functions as an entry factor for severe adenovirus species B infection 5. In lens epithelial cells, ALCAM expression is downregulated in age-related cataracts through miR-34a-5p regulation 6. ALCAM serves as a superior biomarker for mesenchymal stromal cell identification compared to standard ISCT markers 7. These diverse roles suggest ALCAM as a pleiotropic mediator with therapeutic potential across multiple disease contexts.