The cytosolic molecular chaperone Hsp90 is essential for eukaryotic life. It is involved in multiple branches of proteostasis and as a molecular capacitor in morphological evolution. Although reduced Hsp90 levels cause phenotypic variations and correlate with aging, whether eukaryotic cells and organisms can tune Hsp90 levels to alleviate physiologically accumulated stress is unknown. To begin to explore this question, we investigated whether and how mice adapt to the deletion of three out of four alleles encoding cytosolic Hsp90, one Hsp90β allele being the only remaining one. Here we have analysed the proteome of mouse tissues (brain, liver, muscle) corresponding to different Hsp90 genotypes, as well as HEK293 cell clones that were knock-out for Hsp90α/β.