Of the 13 GC cell lines tested in this study, only OE19 and NCI-N87 cells expressed high levels of Her2 protein (Fig. 2a) and correspondingly, only growth of these two lines was inhibited by trastuzumab monotherapy in vitro (Supplementary Fig. S2) with GI50 values of 112 μg/mL and 0.8 μg/mL, respectively. The gene discussed is ERBB2; the disease is gastric cancer.