Figure 4.

Autophagy of nucleus pulposus (NP) cells is refractory to tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) stimulation. (A) Rat nucleus pulposus (NP) cells cultured with serum-free medium showed robust expression of LC3-II in cytoplasm (magnification, ×20). Rat NP cells were treated with TNF-α or IL-1β, and (B) Beclin-1 and (C) LC3-II mRNA showed no change in response to cytokine treatment. (D) Western blot analysis and corresponding (E and F) densitometric analyses of NP cells treated with TNF-α and IL-1β. No significant change was observed in (E) Beclin-1 protein and (F) LC3 protein turnover. Data represent mean + standard error of three independent experiments. ^*P<0.05. PI, propidium iodide; ns, not significant; Ctr, control.