Fig. 3.

Activation of NF-κB in muscle cells or macrophages can directly or indirectly influence muscle cell proliferation and differentiation. Th1 cytokines or oxidative stress can increase NF-κB activation in muscle or macrophages. Those cytokines can then contribute to further activation of NF-κB or they can act on muscle cells to affect their proliferation or differentiation. In general, NF-κB activation increases proliferation and inhibits differentiation, increasing the expression of transcripts needed for cell cycle progression and by decreasing the expression or destabilizing transcripts needed for muscle to experience terminal differentiation. NO, nitric oxide; iNOS, inducible nitric oxide synthesis; ONOO, peroxynitrate; MEF2, myocyte enhancer binding factor-2; MHC, myson heavy chain.