Update information. The GRM02 cells were overexpressed HSP90α protein by transient-transfected with Flag-tagged HSP90α plasmids. We mixed the cells from three individual flask for mass spectrometry, and repeat twice. After 36 h, whole cells were collected in lysis buffer (P0013; Beyotime, Shanghai, China) containing protease inhibitor cocktails (04906837001; Roche, Mannheim, Germany) and phosphatase inhibitor cocktails (04906837001; Roche) and incubated on a rocker with ice for 30 min and centrifugated at 12,000 g/4°C for 15 min to obtain cell lysates. The cell lysates were immunoprecipitated with an anti-Flag magnetic bead (4°C, overnight). The beads were washed three times with lysis buffer, separated by SDS-PAGE, and then stained with Coomassie Blue. The entire lane was excised and digested with trypsin in 25 mM NH4HCO3 at 37°C for 20 h. The peptides were extracted three times with 60% acetonitrile (ACN) / 0.1% trifluoroacetic acid (TFA), followed by pooled and dried completely by a vacuum centrifuge. Chromatography-tandem mass spectrometry (LC-MS/MS) analysis was performed on a Q Exactive mass spectrometer (Thermo Scientific) that was coupled to Easy-nLC 1000 (Thermo Scientific) for 120 min. Raw files generated from the spectrometry were searched using MASCOT engine (version 2.2, Matrix Science, London, UK) and subjected to Proteome Discovere (version 1.4, Thermo Electron, San Jose, CA) against Uniprot_mouse database (76417 sequences, download at December 12th, 2014) and decoy database for protein identification. Additional parameters were as follows: peptide mass tolerance: 20 ppm, MS/MS tolerance: 0.1 Da, missed cleavage: 2, false discovery rate (FDR) ≤ 0.01. The analysis was performed by Applied Protein Technology (aptbiotech, Inc. Shanghai, China).