Figure 3. Combination of ritonavir and delanzomib induced endoplasmic reticulum (ER) stress and autophagy, inhibited mammalian target of rapamycin (mTOR) pathway, and caused histone acetylation in renal cancer cells. A: Western blot analysis for the ER stress markers glucose-regulated protein 78 (GRP78), endoplasmic reticulum resident protein 44 (ERp44), and endoplasmic oxidoreductin-1-like protein (ERO1-L), and for ubiquitinated proteins. Cells were treated for 48 h with 25 or 50 nM delanzomib with or without 50 μM ritonavir. Actin was used as a loading control. Representative blots are shown. B: Western blot analysis for ubiquitinated proteins. Cells were treated for 12, 24, and 48 h with 50 μM ritonavir and 50 nM delanzomib. Actin was used for the loading control. Representative blots are shown. C: Western blot analysis for the autophagy marker light chain 3 (LC3). Cells were treated for 48 h with 25 or 50 nM delanzomib with or without 50 μM ritonavir. Actin was used for the loading control. Representative blots are shown. D: Western blot analysis for sestrin 2, AMP-activated protein kinase (AMPK), mTOR, and S6 ribosomal protein (S6) after 48-h treatment with 25 or 50 nM delanzomib with or without 50 μM ritonavir. Actin was used as a loading control. Representative blots are shown. E: Western blot analysis for acetylated histone after 48-h treatment with 25 or 50 nM delanzomib with or without 50 μM ritonavir. Actin was used as a loading control. Representative blots are shown. F: Western blotting for histone deacetylase (HDAC) 1,-2,-3, and-6 after 48-h treatment with 25 or 50 nM delanzomib with or without 50 μM ritonavir. Actin was used as a loading control. Representative blots are shown.