This fluorescence image depicts an MDA-MB-231 breast cancer cell (green) in the midst of escaping (extravasating) from a blood vessel (red, CD 31) that has been synthesized in an in vitro microfluidic device. The image shows one time-point in a series of time-lapse images following the same cell and was taken to better understand qualitatively the dynamics of tumor-endothelial interactions and tumor cell deformations at a single cell level, during extravasation. Two cancer cells that have already extravasated are found at the bottom of the image.