Lactacystin

CoCl₂ was purchased from Sigma-Aldrich (St. Louis, MO, USA). Protein A-Sepharose was purchased from GE Healthcare Bioscience (Piscataway, NJ, USA). MG132 was purchased from Calbiochem (San Diego, CA, USA). Lactacystin was purchased from Peptide Institute Inc. (Osaka, Japan).

Site-directed mutagenesis of PSMD14 was performed with the QuikChange Lightning Site-Directed Mutagenesis Kit (Agilent Technologies, Santa Clara, CA, USA) and primer sequences described previously^{56 (link)}. MLN4924 (Sequoia Research Products, Pangbourne, UK), MG132 (Fujifilm Wako Pure Chemical), and lactacystin (Peptide Institute, Ibaraki, Osaka, Japan) were purchased from the indicated suppliers. Generation of antibodies against XPC^{69 (link)}, RAD23B^{30 (link)}, and PSMD4^{57 (link)} was described previously. The following antibodies were purchased from manufacturers: XPC (NB100-477, Novus Biologicals, Centennial, CO, USA), DDB2 (AF3297, R&D Systems, Minneapolis, MN, USA), CUL4A (14851-1-AP, Proteintech, Rosemont, IL, USA), multi-ubiquitin (FK2; D058-3, Medical & Biological Laboratories, Nagoya, Japan), mKO2 (PM051M, Medical & Biological Laboratories), PSMD14 (ab109123, abcam, Cambridge, UK), RAD23A (24555, Cell Signaling Technology, Danvers, MA, USA), α-tubulin (T5168, Merck), and lamin B1 (C-20, Santa Cruz Biotechnology, Santa Cruz, CA, USA).