Lapatinib (GW572016, Tykerb) is a dual synthetic reversible inhibitor of EGFR and HER2 tyrosine kinases, and has been demonstrated to inhibit significantly the proliferation of cancer cells evidencing EGFR and/or HER2 overexpression both in vitro and in vivo[1]–[3]. The gene discussed is ERBB2; the disease is cancer.