α4β1

α4β1 integrin (very late antigen-4, VLA-4) is a heterodimeric adhesion receptor that regulates leukocyte trafficking, cell adhesion, and immune cell communication through interactions with vascular cell adhesion molecule-1 (VCAM-1), fibronectin, and related ligands^[3][4]. Mechanistically, α4β1 plays a central role in leukocyte tethering, rolling, firm adhesion, and transendothelial migration during inflammatory responses, thereby controlling immune-cell recruitment to inflamed tissues^[3][4]. Through α4β1-VCAM-1 signaling, activated lymphocytes and monocytes gain access to target organs, linking this integrin directly to inflammatory and autoimmune disease pathogenesis^[3][1]. In disease models, α4β1 is required for T-cell migration across the blood-brain barrier, and blockade of α4-mediated adhesion suppresses experimental autoimmune encephalomyelitis, supporting its relevance to multiple sclerosis and related neuroinflammatory disorders^[3]. α4β1 also contributes to leukocyte accumulation in chronic inflammatory conditions, making it a validated therapeutic target in immune-mediated diseases^[3][1]. Compared with the related α4β7 integrin, which preferentially mediates lymphocyte homing to intestinal tissues through interactions with mucosal addressin cell adhesion molecule-1 (MAdCAM-1), α4β1 primarily mediates adhesion to VCAM-1 and functions broadly in systemic inflammatory trafficking^[2]. This distinction is important for experimental design because α4β1 and α4β7 exhibit overlapping yet biologically distinct ligand-recognition and tissue-homing properties^[2]. For research applications, selective α4β1 antagonists and inhibitory antibodies are widely used to investigate leukocyte migration pathways, whereas highly selective small-molecule inhibitors such as BIO5192 provide experimental tools for dissecting α4β1-dependent adhesion mechanisms with minimal activity toward other integrins^[1].