ERBB2 and cancer: In the past several years, the small molecule tyrosine kinase inhibitor (TKI) lapatinib, which selectively targets both EGFR1 and HER2, has proven to be an effective therapeutic strategy for HER-2-positive metastatic breast cancers [20], while bifunctional and bivalent antibodies, such as anti-HER2 and anti-EGFR1, showing high affinity, are currently being used in cancer diagnosis and treatment [21].