RASD1 and breast cancer: In clonogenic assays with NIH-3T3 murine fibroblast cells, the MCF-7 human breast cancer cell line, and the human lung adenocarcinoma cell line A549, Dexras1 transfection markedly diminished the number of G418-resistant colonies, whereas K-Ras, another member of the Ras protein family, was without effect.