Effect of proteosomal (B) or endosomal (C) protein degradation inhibitor on USP15- (open triangle) mediated degradation of Gag. 293T cells were transfected with 4 μg HIV-1 proviral DNA together with 1, 2, and 4 μg of USP15-expressing plasmid, and at 48 hour post-transfection, cells were treated with DMSO (A) or with either 2 μM MG132 (B) or 100 nM Bafilomycin A1 (C) for 6 hours. WB analysis was then performed with each cell lysate with anti-p24 Ab for p24, and the data were representative of three independent experiments. (D) The amount of p24 in the cells treated with DMSO, MG132, or Bafilomycin A1 (Baf.) of three independent experiments was determined by scanning the corresponding bands, using ChemiDoc Touch Imaging System (Bio-Rad, Hercules, CA), and depicted as mean +/− SD of triplicates.