Indeed, there is now evidence emerging from experimental breast cancer cell models implicating a role for erbB receptors in resistance to IGF-IR blockade, with Haluska and colleagues [47] showing that EGFR/erbB2 signalling can confer resistance to the IGF-IR tyrosine kinase inhibitor BMS-536924 in MCF-7 cells. This evidence concerns the gene ERBB2 and breast cancer.