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. GEF activity is mediated via module of tandem DH-PH domains. Vav proteins also appear to exhibit GEF-independent functions. Although it was originally thought that Vav proteins would only be present in multicellular organisms, Vav family proteins have been observed in Choanoflagellates.
In humans there are three Vav proteins:
References
Vav (protein) Wikipedia(Text) CC BY-SA