Research Paper Volume 12, Issue 17 pp 16837—16851

Figure 5. SFN-Cys increased the expression of 26S proteasome via sustained ERK1/2 phosphorylation to degrade cell cycle-related proteins leading to the cell cycle arrest in G0/G1 and G2/M phases. (A–C). The expressions of CDK4, CDK6 and p-Rb were detected by Western blot after the intervention of 30 μM SFN-Cys with or without MG132 (0.5 μM) for 24 h in U87MG and U373MG cells. (D) The expressions of 26S proteasome, ERK1/2 and p-ERK1/2 were detected by Western blot after the treatment of SFN-Cys (30 μM) with or without PD98059 (25 μM) for 24 h in U87MG and U373MG cells. (E) Both U87MG and U373MG cells were starved for 24 h, and then treated with or without SFN-Cys for 24 h. the cell cycles were detected by flow cytometry via Cell Cycle and Apoptosis Analysis Kit. (F) The cell cycles were detected without starvation. (G, H) The apoptosis rates were detected via Annexin V-FITC/PI staining in U87MG and U373MG cells after treatment of SFN-Cys (30 μM) with or without PD98059 (25 μM) for 24 h. The percentages of apoptotic cells were detected by flow cytometry. Data were shown as *P < 0.05; **P < 0.01; ***P < 0.001, NS no significance vs. control group, n ≥ 3.