As a GEF to activate Rho GTPase, VAV3 participates in multiple biological processes, such as endothelial defensive function, cancer metastasis, and even glucose homeostasis via regulation of GSV directional traffic 18, 29, 42, by switching non-activated GDP-binding GTPases to activated GTP-binding GTPases, such as Rho A, Rac-1, and CDC42 17, 18, 29. The gene discussed is RAC1; the disease is cancer.