STAT6 and graft versus host disease: To determine whether the GVT response can be preserved without causing GVHD-related mortality by directly augmenting Th2-dependent responses, we made use of a mouse model whose T lymphocytes express a constitutively active form of STAT6, in which the expression of the transgene is driven by human CD2 locus control region [14]; this model has historically permitted efficient in vivo protein expression in mice [15].