Cyclooxygenases and UCP1 Figure 4. UCP1 expression is induced by forced expression of COX2 alone or in combination with COX1 in cultured cells. A. Rb2/2 MEFs were induced to differentiate as described in experimental procedures. Differentiated adipocytes were treated with vehicle or isoproterenol (100 nM) and 9-cis-retinoic acid (1 mM) in the absence and presence of the COX1 inhibitor SC560 (50 nM) or the COX2 inhibitor NS398 (5 mM), alone or in combination, or with indomethacin (1 mM), for 24 h. Expression of UCP1 was measured by RT-qPCR. The bars represent mean 6 standard error. The experiment was performed in triplicates and repeated 2 times. B–D. Rb2/2 MEFs were retrovirally transduced with empty vector, vector encoding COX1 or COX2, or both. The transduced cells were selected and induced to differentiate and analyzed for COX1 and COX2 expression by Western blotting (B). PGE2 levels were measured in cell media (C). RNA was isolated on day 8 and expressions of genes were measured by RT-qPCR (D). The bars represent mean 6 standard error. Different letters indicate statistically significant difference (p,0.05). The experiments were performed in triplicates. doi:10.1371/journal.pone.0011391.g004 PLoS ONE | www.plosone.org 6 June 2010 | Volume 5 | Issue 6 | e11391