Indeed, Zhou et al. first demonstrated that TCR-transgenic CD4 T cells specific for a TAA, adoptively transferred into mice bearing TAA-expressing tumor cells, proliferated extensively after administration of a therapeutic tumor vaccine (in the form of a recombinant vaccinia virus encoding the antigen), but tumor-antigen-experienced cells were mostly regulatory cells, ex vivo suppressive, and anergic to subsequent stimulation (81). Here, CD4 is linked to neoplasm.