Pre-treatment with the HSP90 inhibitor, AUY-922, prevents HCl-mediated hyperpermeability of HLMVEC monolayers. HLMVEC were seeded on 8W10E+ arrays until confluent, i.e., until stable resistance was achieved (>800 Ω). (A) HLMVEC were treated with AUY-922 (2 µM) for 24 h and then challenged with 0.01 N HCl (arrow). Resistance was recorded continuously at 10 s intervals and normalized to time = 0 h. (B) The HSP90 inhibitor, AUY-922, added to the media in a final concentration of 2 µM, did not affect HCl-induced decrease in pH. (C) Cell viability of HLMVEC incubated for 24 h with different concentrations of AUY-922 (1, 2, and 10 µM). Means ± SEM; n = 3. **: p < 0.01; ****: p < 0.0001 by one-way ANOVA with Bonferroni’s post-test.