Fig. 4.

Effect of suramin on interleukin (IL)-1β-induced apoptosis in nucleus pulposus (NP) cells. a) The NP cells were treated with 10 ng/ml IL-1β, 10 μM suramin, or suramin plus IL-1β for 72 hours and cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Values are expressed as the mean and standard deviation of triplicate measurements (***p < 0.001 compared with untreated control). b) Western blot was used to measure the protein levels of cleaved polyadenosine diphosphate-ribose polymerase (PARP) in NP cells treated with 10 ng/ml IL-1β, 10 µM suramin, or suramin plus IL-1β for 72 hours. c) NP cells were cultured in the absence or presence of IL-1β with or without the addition of suramin. The percentages of Annexin V/propidium iodide (PI)-positive cells are shown, represented in the boxed regions (n = 3). c, control.