VAV1 and cancer: Consistent with this, various GEFs have been implicated recently in cancer [13, 26], and activation of Vav1 GEF activity following tyrosine phosphorylation has been demonstrated in EGF and PDGF stimulated NIH3T3 fibroblasts expressing Vav1 [22, 23] as well as in cancer cells, including neuroblastoma [68], pancreatic cancer [69] and lung cancer [70].