Ubiquitinated proteins build-up in rheumatoid arthritis synovial fibroblasts with inhibited proteasome or autophagy pathways. (a) Lysates (3 μg) from synovial fibroblasts cultured as indicated with 10 ng/ml TNFα, 0.5 μM proteasome inhibitor (PI) or 12.5 μM chloroquine (CQ) for 24 or 72 hours were immunoblotted and probed for ubiquitinated proteins. (b) Quantification of the blots was determined by ImageJ software. These results are the mean and standard deviation of three different experiments. Significant differences in TNFα-stimulated cultures compared with cultures where PI or the autophagy inhibitor CQ was included in addition to TNFα: *P < 0.05, **P < 0.01.