Drug discovery is a complex undertaking facing many challenges, not the least of which is a high attrition rate as many promising candidates prove ineffective or toxic in the clinic owing to a poor understanding of the diseases, and thus the biological systems, they target. Therefore, it is broadly agreed that to increase the productivity of drug discovery one needs a far deeper understanding of the molecular mechanisms of diseases, taking into account the full biological context of the drug target and moving beyond individual genes and proteins. The present methods rely on the use of label-free cellular assays, particularly the DMR index, to systematically display the mode of actions, the toxicity, and the target(s) and pathway(s) of any molecules.