Figure 2.
MDP treatment reduced phosphorylation of MAPKs via the induction of MAPK phosphatase (MKP)-1 in HDPCs. (A) HDPCs were stimulated with MDP at 10 µg/mL for 120 min in osteogenic media (OM) with 10 mM β-glycerophosphate, 10−7 M dexamethasone, and 50 µg/mL L-ascorbic acid. The phosphorylation of MAPKs and the expression of MKP-1 were determined by Western blotting. (B) HDPCs were pre-treated with MKP-1 inhibitor (Triptolide, TP 0.5 mM) for 4 hr, and stimulated with MDP for 120 min. The phosphorylation of MAPKs was examined by Western blotting. (C) HDPCs were cultured in the presence of MDP or Triptolide for 14 days. At the end of culture, ALP activity was examined. *Statistically significant difference vs. control, p < .05. #Statistically significant difference in OM alone, p < .05. Similar data were obtained from 3 independent experiments.