Figure 4. Effect of inhibiting PLD on protein kinase C (PKC) activity in resting zone (RC) and growth zone (GC) chondrocytes. Confluent, fourth-passage RC cells were treated with 10-7 M 24R,25-(OH)2D3 for 90 min (left panel), and GC cells were treated for 9 min with 10-8 M 1
,25-(OH)2D3 (right panel) in the presence or absence of the phospholipase D inhibitor wortmannin (10 µM). At harvest, PKC specific activity in the cell layer was determined. Data represent the mean ± SEM of 6 cultures from one of two experiments yielding comparable results. *P < 0.05, treatment vs. control; •p < 0.05, wortmannin vs. no wortmannin.
