miR-146a leads to apoptosis in chondrocytes. (A) to (D) TUNEL assays were performed 2 days following the addition of negative control (NC) or miR-146a to chondrocytes. miR-146a increases apoptosis in chondrocytes. The nuclei of apoptotic cells are labeled by TUNEL with green fluorescence. All cell nuclei are counterstained by Hoechst 33342 (blue). Original magnification: (A), (B) ×200; (C), (D) ×600. (E) Quantification of the percentage of TUNEL-positive cells shows a 40.3% increase in the percentage of apoptotic cells in chondrocytes transfected with miR-146a. **P < 0.01.