IGF2 and breast cancer: High expression of insulin-like growth factor 1 receptor (IGF1R) and its two ligands, insulin-like growth factor 1 (IGF1) and insulin-like growth factor 2 (IGF2) have been demonstrated in OS, as well as many other cancers including rhabdomyosarcoma, breast cancer, prostate cancer, and colon cancer [7]–[14].