Thanks to a fortuitous connection in the Koch Café, it is now possible to longitudinally study cancer progression and treatment response in genetically engineered mouse models using circulating tumor cells. A new microfluidic platform, described in Proceedings of the National Academy of Sciences, combines expertise from the Manalis, Jacks, Shalek, and Vander Heiden Lab to capture and genomically profile these vanishingly rare cells from a single awake mouse without depleting the animal’s limited blood supply.