VAV1 and neoplasm: Expression of Vav1 showed no definitive pattern, increasing in NPI2 tumours compared with NPI1 tumours but showing no change in NPI3 tumours (mean ± SEM 0.45 ± 0.22 NPI1; 1.18 ± 1.06 NPI2; 0.45 ± 0.41 NPI3).