FIGURE 4.

Betulin treatment inhibited the activation of NF-κB signal. OA chondrocytes were cultured with betulin (0, 25, 50, and 100 μM) of different concentrations for 2 h, and then stimulated by IL-1β (10 ng/ml) for 24 h. (A–C,F) The protein expression levels of p-p65, p65, IκBα, and p-IκBα were detected by Western blot and quantitatively analyzed. (D,E) Immunofluorescence staining combined with DAPI staining (scale: 25 μm) were used to detect the entry of characteristic index p65 into the nucleus and quantitative analysis of fluorescence intensity. The data in the figure are represented as the mean ± SD, **p < 0.01 compared with the control group, ^@@ p < 0.01 compared with the IL-1β group, n = 3.