Considering xenograft, intraperitoneal injection with 15 mg/kg trastuzumab once every 3 days could not inhibit the growth of pCMV transfected GC cells at any time point (Fig. 3A–D), but the trastuzumab related growth inhibition for pCMV-Dicer-transfected GC xenograft was achieved when compared to pCMV-Dicer and pCMV-Dicer plus Trastuzumab GC cells(p < 0.01; Fig. 3A–D). The gene discussed is DICER1; the disease is gastric cancer.