Figure 1.

Multiple ERK1/2 phosphorylation events are dependent on MEK1/2 signalling. Chondrocytes were pretreated with dimethyl sulfoxide, U0124 (10 μM) or the active mitogen-activated kinase kinase (MEK) 1/2 inhibitor, U0126 (10 μM) for 30 minutes prior to TNFα treatment for 15 minutes or 90 minutes. Cytoplasmic extracts (20 μg) were resolved on 10% polyacrylamide gels and were immunoblotted for pY-extracellular regulated kinase (ERK) 1/2 or total ERK2. Immunoblots are representative of three independent experiments.