Recently, the Ran (Ras-related nuclear protein) and Brms1 (breast cancer metastasis suppressor 1) promoters were shown to display high activity—comparable to the CMV promoter—as well as cancer specificity in vivo in ovarian cancer (Bg-1 cells), prostate cancer (PC-3 cells) and breast cancer (MCF-7 cells) [21]. This evidence concerns the gene RAN and breast cancer.