Fig. 3
Shear-induced cAMP and IGF-2 are responsible for the synthesis of MMP-12 in human chondrocytes. a–c T/C-28a2 chondrocytes were subjected to fluid shear stress (20 dyn/cm2) or static conditions (0 dyn/cm2) for the indicated time intervals. d–f In select experiments, T/C-28a2 chondrocytes were treated with the indicated concentrations of exogenous PGE2 (10 μM) or PGF2α (10 μM). g and h In separate experiments, cells were incubated with forskolin (10 μM) or IGF-2 (10 ng/ml) for 48 h. a, c, d, f The synthesis of cAMP and IGF-2 was determined by enzyme immunoassay kits. Total protein served as the internal control. b and e mRNA expression of IGF-2 was determined by qRT-PCR, and GAPDH served as the internal control. g and h MMP-12 mRNA and protein levels were determined by qRT-PCR and western blots, respectively. GAPDH and MMP-11 served as internal controls in qRT-PCR and western blots, respectively. Data represent the mean ± SE of at least three independent experiments. *p < 0.05 with respect to static control
