ITGA4 (integrin subunit alpha 4) encodes the alpha-4 subunit of integrin heterodimers that function as critical cell adhesion receptors mediating leukocyte trafficking and tissue homing 1. The primary integrin complexes formed are α4β1 (VLA-4) and α4β7, which recognize fibronectin, VCAM1, and MADCAM1 as ligands. ITGA4 plays essential roles in immune cell function, including monocyte differentiation and inflammatory responses. In sepsis-related acute lung injury, ITGA4 on monocytes interacts with VCAM1 on endothelial cell-derived extracellular vesicles, activating NF-κB signaling and promoting proinflammatory macrophage differentiation 2. The gene is implicated in cancer biology, where ITGA4 expression enhances acute myeloid leukemia cell homing and engraftment in bone marrow, contributing to chemoresistance 3. In pancreatic cancer, cancer-associated fibroblasts induce acinar-to-ductal transdifferentiation through a laminin α5/integrin α4/STAT3 signaling axis 1. ITGA4 also functions in natural killer cell cytotoxicity against hepatic stellate cells in liver fibrosis 4. Genetic variants in ITGA4 are associated with inflammatory bowel disease risk, where expression-increasing alleles correlate with increased disease susceptibility 5. The protein serves as a therapeutic target in various diseases, with specific inhibitors being investigated for cancer and inflammatory conditions 6.