Figure 1

COX-2 expression requires Rac1, and Rac1 is overexpressed in papilloma cells. (A) Normal laryngeal epithelial cells and papilloma cells, cultured in serum-free medium containing EGF and insulin, were transfected with small interfering RNAs (siRNA) directed against Rac-1 for 3 days. Control cultures were transfected with Luciferase siRNA. COX-2 and Rac1 protein levels were analyzed by Western blot, quantified by densitometry, and normalized to actin levels. PGE₂ levels in the culture supernatants were analyzed by EIA. A typical Western blot is shown. Results are expressed as the mean ± SD of three separate experiments with each type of cell, expressed relative to the control levels in normal cells treated with luciferase siRNA (*P < 0.01). PGE₂ levels are the mean ± SD of three experiments with each cell type, *P < 0.05 compared with controls of each type treated with luciferase siRNA. (B) Rac1 levels were measured in the cells transfected with luciferase siRNAs from the same Western blots analyzed in A, and levels in papilloma cells expressed relative to the levels in normal cells. Rac1 is overexpressed in papilloma cells (*P < 0.01).