VAV an activator of RAC-GTPases, is redistributed to plasma membrane and is phosphorylated following engagement of FCERI. Phosphorylated SLP-76 tyrosines Y113 and Y128 (112Y and 128Y in mouse) provide binding sites for the SH2 domains of VAV. The binding of VAV to these phosphotyrosine residues may link SLP-76 to the Jun amino-terminal kinase (JNK) pathway and the actin cytoskeleton (Kettner et al. 2003).
In addition to its known role as guanine nucleotide exchange factor (GEF), VAV also modulates cytokine production in mast cells. VAV1-deficient bone marrow-derived mast cells exhibited reduced degranulation and cytokine production and calcium release in addition of reduced activation of c-Jun NH2-terminal kinase 1 (JNK1), although tyrosine phosphorylation of FCERI, SYK and LAT was normal (Manetz et al. 2001, Arudchandran et al. 2000, Song et al. 1999).