Compared with the percentage of (i)Tregs induced by BC-derived cells following the administration of shControl, the percentage of CD4+Foxp3+ (i)Tregs induced by BC-derived cells was significantly reduced (P < 0.05) following the administration of siRNA-S1P1 or shRNA-S1P1 or in the presence of anti-TGF-β and anti-IL-10 antibodies and was inversely increased by forced S1P1 expression or in the presence of FTY720 (Fig. 2a, b, and Fig. S1c and d). Here, CD4 is linked to breast cancer.