ABSTRACT
The factor that drives this approach is specificity. The driving force for many in drug discovery is to find agents that are more specific for a particular molecular target because that should enhance efficacy, reduce side effects, and yield an agent that is unique to a particular pathology. However, the task is very daunting, as one can see by going down the list of molecular targets in Figure 7 and thinking about the implications. For instance, we are good at finding specific inhibitors of enzymes, but there are multiple classes, and even within classes there are isozymes. Similarly, with receptors, there are isoforms. Receptors are found not only in the plasma membrane but in the cytoplasm and nucleus as well. Ion channels have multiple subunits. The complications go on and on. There is, in each one of these cat-
