The immunogen used for the anti-human Vav-2 DPH region was a his tagged fusion protein Vav-2 corresponding to amino acid sequence 287-578 and having a molecular weight of 100kD. Vav-2 has a molecular weight of 100 kD and shares over a 50% homology at the amino acid and nucleic acid level with Vav. Vav-2 is a ubiquitously expressed structural homolog of the Vav protooncogene that is expressed preferentially in hematopoetiic cells. Both proteins are comprised of a Dbl- homology ((DH) domain with guanosine nucleotide exchange (GEF) activity exclusively directed towards Rho/Rac GTPases, a pleckstrin homology (PH) domain, a calponin-homology (CH) region, an acidic domain (AD) a zinc finger butterfly motif, two SH3 regions and one SH2 domain. GEF activity of RhoA family G proteins is induced by tyrosine phosphorylation in wild type vav-2, and is constitutively activated in N terminus deleted oncogene forms. Constitutive expression of a Vav-2 oncoprotein may result in morphological alterations including highly enlarged cells in which karyokinesis and cytokenesis frequently are uncoupled. Synonyms: VAV-2, Guanine nucleotide exchange factor VAV-2, Dbl homology (DH) domain.