The Hsp90 molecular chaperone catalyses the final activa-tion step of many of themost important regulatory proteins of eukaryotic cells. The antibiotics geldanamycin and rad-icicol act as highly selective inhibitors of in vivo Hsp90 function through their ability to bindwithin the ADP/ATP binding pocket of the chaperone. Drugs based on these compounds are now being developed as anticancer agents, their administration having the potential to inactivate sim-ultaneously several of the targets critical for counteracting multistep carcinogenesis. .
