NF-κB-targeted bortezomib treatment does not impact tumor cell proliferation in vivo. Subcutaneous (A, B) and pleural (C, D) tumor tissue was obtained on days 28 and 14, respectively, from experiments described in Figure 3 and was immunostained for proliferating cell nuclear antigen (PCNA; A, C) and terminal deoxynucleotidyl nick-end labeling (TUNEL; B, D), indicators of cell proliferation and apoptosis, respectively. Shown are summary of results and representative photomicrographs (Å = 600; scale bars = 50 μm). NF-κB-targeted bortezomib treatment had no effect on Lewis lung carcinoma (LLC) cell proliferation in subcutaneous or pleural tumors (A, C). However, bortezomib treatment resulted in enhanced apoptosis rates in both tumor sites (B, D). n, sample size; P, probability values; hpf, high-power field. Dots, raw data points; lines, mean; bars, standard error of mean. #, ##, and ###: P < .05, .01, and .001, respectively, compared with control.