miR-320a overexpression enhanced IL-1β-induced matrix degradation by regulating NF-κB. (a) C28/I2 cells were treated with MG132 for 24 hours, and the expression of miR-320a was monitored by RT-PCR. C28/I2 cells were transfected with miR-320a and/or treated with MG132, and the expression of (b) Col2α1 and the concentration of MMP-13 (c) were measured by RT-PCR and MMP-13 ELISA kit, respectively. *, p < 0.05; **, p < 0.01. Statistical analysis was performed using two-tailed paired t-test.