RADIL (Rap associating with DIL domain) functions as a downstream effector of Rap1 GTPase that regulates cell adhesion and migration through integrin activation. RADIL mediates Rap1's effects on endothelial barrier function by connecting to Rho GTPases, actomyosin cytoskeleton, and cell-cell adhesion receptors 1. In neutrophils, RADIL controls β1- and β2-integrin activation, translocating from cytoplasm to plasma membrane upon Rap1a-GTP activation to facilitate chemotaxis and adhesion 2. RADIL also interacts with all Ras isoforms, particularly KRas, and may function as a Ras activator, promoting MAPK/ERK signaling and epithelial-mesenchymal transition 3. During neural crest development, RADIL acts downstream of protogenin to activate α5β1-integrins, preventing premature apoptosis of rostral cephalic neural crest cells 4. Disease relevance includes potential involvement in lipomyelomeningocele through variants in RADIL combined with ARHGAP29 5, and interaction with SARS-CoV-2 E protein, which may affect viral replication 6. RADIL participates in multiprotein complexes that coordinate endothelial junction tightening through both Rho inhibition and Cdc42-mediated tension 7. These functions establish RADIL as a critical regulator of cell adhesion, migration, and barrier function across multiple biological contexts.