Delivery of siNanog into tumor-bearing mice suppressed the growth of tumor cells [TC-1 (mouse lung), HEK293 (human embryonic kidney), and CaSki (human cervical)] [2], suggesting the in vivo tumor-promoting effect of Nanog. The metastatic potential of mammary tumors to the lungs in Nanog and Wnt-1-overexpressing mice was 5–6 times higher than that in Wnt-1-overexpressing mice [3], which highlighted the growth promotion, but not tumorigenesis, by Nanog. In ES-2 ovarian cancer cell lines, Nanog was controlled by Hexokinase2 (HK2) [4]. Here, WNT1 is linked to breast cancer.