Tumor Cells Invade Bone (image) Princeton University Caption Researchers at Princeton University have found that microRNAs -- small bits of genetic material capable of repressing the expression of certain genes -- may serve as both therapeutic targets and predictors of metastasis, or a cancer's spread from its initial site to other parts of the body. In this image, breast cancer cells (right) spread toward the hindlimb bone (left), using the host's own bone-destroying cells (osteoclasts) to continue their advance. Credit (Image courtesy of Yibin Kang, Department of Molecular Biology) Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.