Some years ago we found that BRG mice are superior to nude mice for studies of metastatic dissemination of human sarcomas (Nanni et al., 2010), therefore we compared the metastatic capacity of human HER-2+ breast cancer cell lines MDA-MB-453 and BT-474 in nude and in BRG mice (Nanni et al., 2012). Here, ERBB2 is linked to breast cancer.