Vav1 GEF activity is required for T cell mediated allograft rejection

► The contribution of Vav1 GEF activity to allograft rejection was addressed. ► T cells with disrupted GEF activity showed reduced proliferation and activation. ► Mice with disrupted Vav1 GEF activity showed prolonged cardiac allograft survival. ► Vav1 GEF activity significantly contributes to T cell-mediated allograft rejection.