A. Inhibition of Hsp90 in Drosophila reveals phenotypes including black facets in one eye, notched wings, and extraneous tissue (reprint from Rutherford and Lindquist, 1998). B. Inhibition of Hsp90 by geldanamycin in A. thaliana reveals phenotypes including disruption of typical symmetry and oval shaped, flat leaves (reprint from Queitsch et al., 2002). C. Inhibition of Hsp90 in Mexican cavefish, A. mexicanus, results in variable eye size of larval fish (reprint from Rohner et al., 2013). D. Human cells expressing the FANCA mutant allele R880Q exhibit increased sensitivity to Hsp90 inhibitor ganetespib but a wild-type allele or non-buffered alleles do not. In this case, the detrimental growth phenotype revealed upon Hsp90 inhibition is only observed in a specific FANCA mutant background (reprint from Karras et al., 2017).