VAV3 is a guanine nucleotide exchange factor (GEF) that primarily activates Rho family GTPases (RhoA, RhoG, and Rac1) by catalyzing GDP-to-GTP exchange 1. It functions as a phosphorylation-dependent molecular switch that cycles between inactive and active conformations to regulate downstream signaling 1. VAV3 plays critical roles in angiogenesis, cell migration, and cytoskeletal organization through Rho GTPase activation 2. In immune cells, VAV3 mediates integrin and B cell receptor signaling, facilitating cell adhesion, phagocytosis, and proliferation 2. Clinically, VAV3 is implicated in multiple disease contexts. In cancer, elevated VAV3 promotes proliferation, epithelial-mesenchymal transition, migration, invasion, and chemoresistance 1. In rheumatoid arthritis, VAV3 overactivation drives pannus formation through enhanced neovascularization and osteoclast-mediated bone destruction 2. VAV3 variants (rs7528153 and rs1185222) associate with hypertension susceptibility, likely through Rho/Rac pathway modification in vascular smooth muscle 3. Emerging evidence suggests VAV3 regulates glucose and lipid metabolism, with potential relevance to diabetes and metabolic complications 4. In primary open-angle glaucoma, VAV3 dysregulation was identified as a hub gene in disease pathogenesis 5. These diverse roles position VAV3 as a potential therapeutic target across oncological, inflammatory, cardiovascular, metabolic, and neurodegenerative disease contexts.