This model highlights the importance of Vav1 adaptor functions in the differentiation of CD4 T cells into Th1/Th17 subsets and suggest that genetic or acquired alterations in Vav1 signaling could play a major role in susceptibility to the many immune-mediated diseases, including autoimmune diseases where Th1/Th17 play a preponderant role. The gene discussed is CD4; the disease is autoimmune disease.