Exposure of chondrocytes to lower shear stress inhibits peripheral blood-macrophage-conditioned medium (PB-MCM)-induced urokinase-type PA (uPA) expression. Chondrocytes were kept as controls (CL), or subjected to different levels of shear stress with PB-MCM stimulation. Static chondrocytes were stimulated with PB-MCM without shearing (static). All bar graphs represent fold differences compared with control chondrocytes (CL), mean ± SEM. *P < 0.05 versus CL cells. #P < 0.05 versus static chondrocytes with PB-MCM stimulation. (A) uPA mRNA levels determined by real-time PCR analysis. The mRNA data are presented as the fold changes in fluorescent intensities compared with CL cells normalized to the 18S rRNA levels. (B) The phosphorylation of JNK and Akt after 10 minutes of PB-MCM stimulation was determined by Western blotting. The results are mean ± SEM. All bar graphs represent folds of CL and are normalized to total JNK or Akt. (C) NF-κB p65 binding to the uPA promoter after 1 hour of PB-MCM stimulation was analyzed by ChIP assay by using a p65 antibody. All bar graphs represent folds of CL and are normalized based on the input DNA.