FIGURE 2.

Effect of ARNT on EGF-induced gene expression of COX-2. A, luciferase vector bearing the COX-2 gene promoter was constructed (pXC918) (25). Cells were transfected with pXC918 and ARNT expression vector by lipofection. Cells were treated with 50 ng/ml EGF and further cultured in fresh medium up to 6 h. The luciferase activities and protein concentrations were then determined and normalized. Values represent means ± S.E. of three determinations. B, cells were transfected with pXC918 and various amounts of ARNT siRNA oligonucleotides by lipofection. After EGF treatment for 6 h, the luciferase activities and protein concentrations were determined and normalized. Values represent means ± S.E. of three determinations. Expressions of ARNT and β-actin proteins were analyzed by Western blot analysis using anti-ARNT and anti-β-actin antibodies, respectively. C, cells were transfected with 50 nm ARNT siRNA or scramble oligonucleotides by lipofection. After EGF treatment for 6 h, total RNA was extracted for reverse transcription PCR with COX-2, ARNT, and glyceraldehyde-3-phosphate dehydrogenase primers. D, expressions of COX-2 and c-Jun proteins were analyzed by Western blot analysis using anti-COX-2 and anti-c-Jun antibodies, respectively. The relative density of COX-2 protein was quantified as indicated.