Isothermal dose-dependent fingerprint (ITDRF) CETSA: Based on the previously determined IC50 values, K562 cells were treated with the indicated dilution range of inhibitor for 24h. Then, cells were harvested by centrifugation (400 x g for 5 min at RT) and washed three times with PBS. The pellets were dissolved in 200 µL PBS and transferred into PCR tubes (Eppendorf). Results of prior CETSA runs were utilized to determine the optimal melting temperature of 54.1°C for Hsp90. Samples were heated once at 54.1°C for 3 min (T-Gradient Cycler, Biometra) and then snap-frozen in liquid nitrogen and thawed at 25°C in a thermal cycler (GeneAMP PCR System2700, Applied Biosystems) three times, followed by centrifugation at 10000 x g for 20 min at 4°C. The supernatants were harvested and protein levels were measured by quantitative simple western immunoassay (JESS, BioTechne, MN, USA).