Deciphering the role of CD4+ T cells in cancer is complicated by the existence of several functional subsets such as T helper 1 (Th1) (15), Th2 (15), Th17 (16, 17), regulatory T (Treg) (18), and follicular helper T (Tfh) cells (19), which have very different and antagonizing properties. The gene discussed is CD4; the disease is cancer.