Figure 5.

Iloprost acts via cAMP/Epac/Rap1 to reverse celecoxib-induced IGF-I resistance. A–C, Primary bovine chondrocytes were incubated in serum-free medium and indicated additions for 1 hour before the addition of IGF-I (100 ng/mL) or vehicle for 15 minutes. Cell lysates were analyzed by Western blotting for total and phospho-ERK1/2 as a measure of ERK activity. D, Cells in serum-free medium were incubated with increasing concentrations of CEL for 12 hours, then IGF-I (100 ng/mL) was added for 15 minutes, and cell lysates were analyzed by Western blotting for total and phospho-ERK1/2. All blots shown are representative of at least 3 separate experiments. The media from cells treated as above were assessed for PGE₂ and PGI₂ content by EIA; n = 6, * P < .05 by ANOVA with Newman-Keuls post hoc correction (as compared with IGF-I only sample).