GHR-KO mice are characterized by a very low incidence of cancer [34-36], and one plausible explanation of this fact is that a low circulatory and ovarian IGF-1 level in GHR-KO keeps stem cells, including very small embryonic-like stem cells (VSELs), in quiescence and thus protects them from uncontrolled proliferation [37]. Here, IGF1 is linked to cancer.