Vav is a family of proteins involved in cell signalling.
They act as guanine nucleotide exchange factors (GEFs) for small G proteins of the Rho family.
[1][2] GEF activity is mediated via module of tandem DH-PH domains.
[2] Some functions of the Vav protein are important for the immune system.
Specifically the ability of Vav to change the cytoskeletal structure of lymphocytes, which is particularly used to "aim" cytokines towards bound pathogens or cells.