Frequency of mutations of HER2 and HER3 was found to be 9.8% and 11.8%, respectively, which accounted for ErbB signaling pathway activations in GBC.58 Supporting the evidence, these activated mutations of HER2/3 in GBC cell lines resulted in a significant increase in cell proliferation and tumor development in animals,59 underscoring the essential role of HER2/3 mutations in the development of GBC. The gene discussed is ERBB2; the disease is neoplasm.