Although molecular structure-based modeling and simulations provide us with insights into mechanisms of interactions and biological activities, understanding physiological and biomedical implications often requires more holistic approaches, broadly referred to as systems biology methods, which take account of the cellular context. Our laboratory is examining protein-protein and protein-drug interactions and their effects on cellular signaling, regulation and apoptotic events, using various theoretical and computational approaches, ranging from mathematical models based on simple mass-action kinetics ^1,2 to quantitative systems pharmacology methods.³