CD4 and cancer: In addition, cancer cells recruit FOXP3+ regulatory T cells (Tregs), Th2 T cells and myeloid-derived suppressor cells (MDSCs) and trigger the exhaustion of T cells, which play a more dominant role compared to cytotoxic immune cells, such as effector CD8+ T cells, NK or NKT cells and γδ T cell or effector CD4+ T cells, during cancer progression.