IGF1 and cancer: Nuclear IGF-1R traffics from the plasma membrane (97) and the levels of IGF-1R nuclear translocation are proportional to ligand-induced kinase activation, because its translocation in cancer cells can be inhibited by xentuzumab, an IGF-1/2 neutralizing antibody, or by inhibition of IGF-1R endocytosis (20, 53, 54).