IGF1 and cancer: Many cancers including PCa downregulate cell surface Class I12; it was shown 30 years ago by Trojan and colleagues that this defect could be rescued in rat high grade glioma (HGG) cells by IGF-1 depletion, rendering the cells non-tumorigenic and able to induce CD8 + cytotoxic T-cell infiltration and regression of unmodified tumors in syngeneic animals13.