Cellular engineering is the understanding and control of cellular behavior for developing novel diagnostic medical tools and therapeutics, or harnessing cellular function for commercial applications. In this talk, I shall discuss our research in this burgeoning area aimed at developing in vitro models for arterial thrombosis and breast cancer, and also a commercially viable cytotoxicity screen. First, our results on the kinetics of interaction between platelet receptor and a subendothelial protein that mediate arterial thrombosis and hemostasis will be presented. Our dynamic studies indicate that this interaction is transient and rapid, and may partly explain the pathophysiology of thrombus formation. Next, I will discuss our on-going attempts at delineating the pathways that lead to the selectivity of anti-cancer drugs on cancerous and non-cancerous human mammary epithelial cells. Finally, I shall demonstrate the application of a high-throughput mammalian cell-based assay, which can provide a rapid, inexpensive and convenient evaluation of drug toxicity.