Mark’s professional development focused on improving the lives of individuals suffering from disease. Formal training in mechanical and biomedical engineering gave him the tools to approach diverse problems from a common theme: to reframe difficult biological questions into tractable engineering problems. Collaborating with researchers from various disciplines, Mark brought together novel theoretical and extensive experimental techniques to quantitatively characterize physiological systems at the organ, cellular, and subcellular levels. His most recent work focused on engineering novel, microphysiological systems in which to quantitatively characterize extravasation of single cancer cells and cancer-cell clusters from microvascular networks and engineered capillaries to improve our understanding of cancer progression.