IGF-1R is highly expressed by ES cells, and many studies have demonstrated the importance of the IGF-1R pathway in ES tumor models (van Valen et al., 1992; Hofbauer et al., 1993; Scotlandi et al., 1996, 1998; Toretsky et al., 2001; Kolb et al., 2008). This evidence concerns the gene IGF1R and neoplasm.