Although Marx et al. [30] reached the conclusion that HER-2 amplification was highly homogenous in gastric cancer, and even a whole-tissue section cannot be guaranteed to contain all the HER-2/neu overexpression/amplification, it is a fact that intratumoral heterogeneity for HER-2/neu overexpression/amplification was found to be more common in gastric cancer than in breast cancer. The gene discussed is ERBB2; the disease is breast cancer.