RRAS2 and breast cancer: Altogether, the results in Fig. 2 show that high expression of human RRAS2 is required to maintain the oncogenic properties of a mouse BC cell line derived from a knock-in mouse line overexpressing human unmutated RRAS2. These findings demonstrate that RRAS2 overexpression not only drives the generation of BC in mice but that it is also necessary to maintain the malignant phenotype, bringing the research full circle.