Protein-protein interactions and cancer: small molecules going in for the kill.

There has been much progress in the discovery of small, organic molecules that inhibit protein-protein interactions, particularly in the field of cancer. Tubulin polymerization represents a classic target whose function can be allosterically modulated by small molecules. Several protein-protein complexes that regulate apoptosis, or programmed cell death, appear to be particularly amenable to inhibition by small molecules, and recently described compounds have helped to characterize Bcl-2, MDM2 and XIAP as drug targets. Additionally, small-molecule antagonists have recently been described for several new targets, including Rac1-Tiam1, beta-catenin-T cell factor (Tcf), and Sur-2-ESX. Not only is the list of protein-protein inhibitors growing, but the inhibitors themselves are moving closer to treating disease.