Prostate cancer cell lines LAPC4 and LNCaP were purchased from American Type Culture Collection (ATCC, Manassas, VA). RPMI media, SILAC RPMI media, fetal bovine serum (FBS), dialyzed fetal bovine serum (dFBS), Geneticin (G418), puromycin, 100 U/mL penicillin/streptomycin were from Life Technologies (Grand Island, NY). SILAC isotopes: 13C614N4-l-lysine (k6) and 13C615N4-L-arginine (R10) were from Cambridge Isotope Laboratories, Inc. (Tewksbury, MA). OptiPrep was from Sigma-Aldrich (St. Louis, MO). Mouse anti-ALIX (1A12) was from Santa Cruz Biotechnology (Dallas, TX), and the rabbit anti-FUT8 was a kind gift from Drs. Ruey-Bing Yang and Chen-Fen Tu (Institute of Biomedical Sciences, Academia Sinica, Taipei).28 (link) NuPAGE precast gels and NuOAFE MES running buffer were from Thermo Fisher Scientific (Waltham, MA). Trypsin was from Promega (Madison, WI), and lysyl endopeptidase was from Wako Laboratory Chemicals USA (Richmond, VA). BCA assay kit Pierce was from Thermo Fisher Scientific (Rockford, IL). C18 SepPak columns and Oasis MAX extraction columns were purchased from Waters Corporation (Milford, MA). C18 solid-phase extraction disks were from 3M (St. Paul, MN).