A cluster of circulating tumor cells (CTCs) from a breast cancer patient was captured on HB-Chip, and stained positive for mesenchymal markers (red) and weakly positive for epithelial markers (green) by RNA-ISH. Nuclei were stained with DAPI (blue). Fluorescent image was merged with DIC image. This image relates to a paper that appeared in the Feb. 1, 2013, issue of Science, published by AAAS. The paper, by Min Yu at Massachusetts General Hospital Cancer Center in Charlestown, Mass., and colleagues was titled, "Circulating Breast Tumor Cells Exhibit Dynamic Changes in Epithelial and Mesenchymal Composition."