Effects of mangiferin on the phosphorylation of the Smad and SOX9 signaling pathways in IL-1β-stimulated mesenchymal stem cells (MSCs). (A) Mangiferin upregulates the phosphorylation of Smad 2, Smad 3, Smad 1/5/8, and the SOX9 signaling pathways. MSCs were prestimulated with IL-1β (5 ng/mL) for 1 h and then treated with the indicated dose of mangiferin for 72 h. Whole cell lysates were subjected to Western blotting with the indicated antibodies; (B,C) SOX9 deficiency inhibits the phosphorylation of Smad 2, Smad 3, Smad 1/5/8, aggrecan, and Col2α1. β-actin served as an internal control. MSCs were transfected with control siRNA or SOX9 siRNA and then treated with or without mangiferin for 72 h. Whole cell lysates were subjected to Western blotting with the indicated antibodies. siRNA targeting SOX9 was transfected into two different experiments.