786-O WT and BAP1-KO cells were cultured in heavy (13C6-L-arginine, 13C6-L-lysine, Cambridge Isotope Lab) and light (unlabeled L-arginine and L-lysine) SILAC RPMI-1640 medium (Thermo Fisher Scienific), respectively. After more than 10 passages, cells were lysed with 8 M urea and 5 mg protein from each group were mix. The ubiquitinated peptide enrichment was performed using PTMScan® (Cell Signaling Technology, #5562) following the manufacturer’s instructions.