Figure 6.

p38 MAPK is involved in the up-regulation of NR4A1 by TNF. Western blot is used to detect NR4A1 protein level in treated cells. GAPDH is an internal reference. The experiments are repeated five times. The cultured chondrocytes are treated with TNF for 12 h and then SB203580 (the specific inhibitor of p38) or SP600125 (the specific inhibitor of JNK) for 24 h. SP600125 does not affect the up-regulation of NR4A1 by TNF, while SB203580 inhibits the promotive effects of TNF on NR4A1. NR4A1, nuclear receptor subfamily 4, group A, member 1. TNF, tumor necrosis factor.