Figure 4. Overexpression of p21 increased the anti-oxidative stress response and decreased the ratio of apoptotic ATDC5 cells exposed to IL-1β and EC-Exos. ATDC5 cells transfected with Lenti-NC or Lenti-p21 were exposed to 10 ng/ml IL-1β ± EC-Exos (100 μg) for 24 h. (A) Protein expression of p21 and β-actin in ATDC5 cells treated with IL-1β or IL-1β and EC-Exos at different concentrations (50 and 100 μg). (B) Immunofluorescence assay of Nrf-2 in ATDC5 cells under different treatments. (C) Protein level of p21, C-caspase3, Bcl-2, Bax, NQO-1, HO-1, Keap-1, Nrf-2 and β-actin in ATDC5 cells treated with various methods. (D) TUNEL assays were used to detect apoptosis in ATDC5 cells under different treatments. (E) ROS content in ATDC5 cells under different treatments (F) Flow cytometry was used to detect apoptosis in dyed ATDC5 cells exposed to different experimental treatments.