CD4 and cancer: Unfortunately, we and others have demonstrated that TAA (such as EphA2 and MAGE6)-specific, Th1 cell function is deficient in many cancer patients and that increased frequencies of TAA-reactive Th2- or Treg-type CD4+ T cells may be functionally dominant in vivo (17, 18), leading to a suppression of anti-tumor CD8+ T cell function (19, 20).