Preclinical work has demonstrated that IGF-1R could be used as a successful co-target with EGFR (Chakravarti et al, 2002) and HER2/erbB2 (Lu et al, 2001; Camirand et al, 2002), and in the latter study, synergistic inhibition of proliferation was observed in co-targeted breast cancer cells. Here, ERBB2 is linked to breast cancer.