FIGURE 7.

Berberine decreased the STAT4 protein level via the ubiquitin-proteasome pathway. A, naive CD4⁺ T cells from NOD mice were cultured at the indicated conditions in the absence or presence of berberine for 24 h, and cell lysates were subjected to Western blotting. B, naive CD4⁺ T cells from NOD mice were cultured in the absence or presence of the indicated conditions of berberine or MG132 for 24 h, and cell lysates were subjected to Western blotting. C, naive CD4⁺ T cells from NOD mice were cultured in the absence or presence of the indicated conditions of SB-202190 and SP600125 for 24 h, and cell lysates were subjected to Western blotting. D, naive CD4⁺ T cells from NOD mice were cultured in the presence of berberine or SB-202190 or SP600125 at the indicated conditions for 24 h, and cell lysates were immunoprecipitated (IP) with a monoclonal antibody against STAT4 followed by Western blotting (IB) against ubiquitin and STAT4. Actin was used as a loading control.