VAV1 antibody targets the VAV1 protein, a guanine nucleotide exchange factor (GEF) primarily expressed in hematopoietic cells. Discovered in the 1980s, VAV1 plays a critical role in intracellular signaling pathways, particularly downstream of T-cell receptors (TCRs) and B-cell receptors (BCRs). It contains multiple functional domains, including a Dbl-homology (DH) domain responsible for activating Rho/Rac GTPases, which regulate cytoskeletal dynamics, gene transcription, and immune cell activation. Dysregulation of VAV1 is linked to autoimmune disorders, immunodeficiencies, and cancers. For example, gain-of-function mutations in *VAV1* are observed in peripheral T-cell lymphomas and other hematologic malignancies, driving aberrant cell proliferation and survival. VAV1 antibodies are essential tools in research to study its expression, post-translational modifications (e.g., phosphorylation), and interactions in immune signaling. Clinically, these antibodies aid in diagnosing malignancies with VAV1 alterations and exploring targeted therapies. Recent studies also implicate VAV1 in non-hematopoietic cancers, such as pancreatic and lung adenocarcinomas, expanding its relevance in oncology. As research continues, VAV1 antibodies remain pivotal for unraveling its pathophysiological roles and therapeutic potential.