The primary tumor samples thus included fat pad tumors formed by 231-Luc or HCC1937 cells, whereas the metastatic tumor samples comprised brain metastases formed by breast cancer cells (231-Luc, HER2-60, and HER2-90) or melanoma cells (MeWo, WM3734) as well as bone metastases formed by breast cancer cells (231-Luc, HER2-60, and HER2-90) or melanoma cells (MeWo). The gene discussed is ERBB2; the disease is breast cancer.