But VIP can act directly on the Teff cells – culture of CD25−Foxp3− Teff with VIP induces their differentiation into CD25+Foxp3+ Treg that express high levels of IL-10 and CTLA4 and are protective in a mouse model of graft versus host disease (GVHD) (246). Here, FOXP3 is linked to graft versus host disease.