Indeed, during the last years several evidences have been accumulated pointing to a key role of this receptor in tumorigenesis and cancer progression both as a node in ligand-induced signalling by members of the EGFR family [20] and as a major contributor of resistance to therapies in lung and breast cancer [21-23], which fueled efforts towards the development of ErbB3 inhibitors [24]. This evidence concerns the gene ERBB3 and cancer.