Fig. 4.

The activity of NF-κB signaling in OA chondrocytes. The NF-κB signaling is activated by a variety of ligands, including TNFα, IL-1β, and LPS, leading to phosphorylation (P) and proteasome degradation of IκB. Receptors of NF-κB signaling include TNFR, TLR, LTβR and etc. Activated IKKs lead to IκB degradation by regulating its phosphorylation. Thus, the translocation of NF-κB to the nucleus results in the transcription of the downstream target genes encoding RUNX2, MMPs, ADAMTS, and HIF2α