miR-300 inhibits the experimental lung metastasis in vivo. A. Images of lungs from all mice intravenously injected with MDA-MB-231 cells and with MDA-MB-231cells over-expression of miR-300 (n = 7). B. The histological examination of metastatic nodules. C. The mean lung weights of the different experimental groups. D. The number of tumor nodules on the lung surface of the different experimental groups. E. Expression of Twist was analyzed by Western blot in lung homogenates from four randomly selected animals in both groups. * P < 0.05.