In patients, high levels of ErbB3 expression predict early escape from trastuzumab therapy (Smith et al, 2004), and escape of at least six different breast cancer cell lines from small-molecule TKIs in vitro correlates with activation of ErbB3 and concomitant signalling through the Akt pathway (Sergina et al, 2007). This evidence concerns the gene ERBB3 and breast carcinoma.