Effect of AMPK on peripheral blood-macrophage-conditioned medium (PB-MCM)-induced urokinase-type PA (uPA) expression. All bar graphs represent folds of control chondrocytes (CL) and are normalized to 18S rRNA. The results are shown as mean ± SEM. (A) Chondrocytes were kept as CL or stimulated with PB-MCM for 2 hours. Before being kept as CL or stimulated with PB-MCM, cells were pretreated with 0.5 to 1 mM AICAR for 2 hours. *P < 0.05 versus CL chondrocytes. #P < 0.05 versus DMSO-treated chondrocytes (vehicle control) with PB-MCM stimulation. (B) Chondrocytes were kept as CL, or subjected to 2 dyn/cm2 of shear stress (SS) with PB-MCM stimulation. Cells were treated with 10 mM compound C or transfected with si-CL or si-AMPK. Static chondrocytes were stimulated with PB-MCM without shearing (static). *P < 0.05 versus CL, vesicle control (SS + DMSO), or control siRNA-transfected (SS + si-CL) cells with PB-MCM stimulation. #P < 0.05 versus compound C-treated (SS + com C) or AMPK siRNA-transfected (SS + si-AMPK) cells with PB-MCM stimulation.