Cytokine and COX-2 expression profile in 3T3-L1 preadipocytes and differentiated adipocytes. (A) 3T3-L1 cells were incubated with adipocyte differentiation reagents (250 nM dexamethasone, 450 μM 3-isobutyl-1-methylxanthine, and 167 nM insulin) for two days followed by incubation with insulin (167 nM) for an additional three days. Total RNA was extracted from 3T3-L1-derived adipocytes and BV-2 murine macrophages, converted to cDNA and subjected to PCR analysis using primers specific for Mac-1 and F4/80. β-actin amplification was performed in parallel as a loading control. (B) 3T3-L1 cells were cultured without (preadipocytes) or with (adipocytes) differentiation reagents as described for (A). Total RNA was extracted from cells and processed for PCR analysis using primers for the indicated genes. Amplification of leptin sequence confirmed differentiation of preadipocytes.