Updated FTP location. Heat shock protein 90 (Hsp90) is a major hub in the protein network that maintains cellular homeostasis and function. The qualitative and quantitative changes and rewiring of this protein network in tumor cells make them vastly dependent on Hsp90, and as a consequence its inhibition creates a profound transformation in the proteome. Here, we analyze our most recent effort that take advantage of the druggability of Hsp90 in order to understand the global changes at the proteome level that this inhibition produces. The considerable impact that the targeting of Hsp90 has on the structure of these protein networks shows that the interactome becomes laxer and presumably less efficient in communicating changes and stimuli to maintain cellular homeostasis. The lack of a systematic and proteome-wide study with genetically really comparable and matched normal and cancer cells that address the differential sensitivities to Hsp90 inhibitors, motivated us to conduct one. The transformation of NIH-3T3 cells from normal to tumoral with an oncogenic Ras mutant (Ras-T) establishes a new program of protein abundance that is efficiently targeted by Hsp90 inhibitors. Surprisingly, three different inhibitors (Geldanamycin"GA", PU-H71"PU" and Pochoxime"PX") affect a characteristic set of actors of this program. Studies like the one presented here, showing how the human proteome is changed and shaped by targeting Hsp90 could set the stage for the pharmacoproteomic profiling of responses to sets of different inhibitors and of cancer types with different molecular backgrounds. These drug-profiling analyses will be essential for the development of tailored Hsp90 inhibitors for the treatment of different tumor types and for the use in personalized medicine.