On the one hand, some types of immune cells such as nature killer (NK) cells, B cells were shown to suppress growth of cancer cells and higher number of these cells associated with better prognosis [5]–[7]; on the other hand, studies demonstrated that other types of immune cells including macrophages, FOXP3+ regulatory T cells (Tregs) actually facilitated and promoted the expansion and development of cancer [8]–[10]. The gene discussed is FOXP3; the disease is cancer.