To confirm the inhibitory effect of TTF-1 on the transcription of the COX-2 gene, we performed promoter assays using a luciferase construct containing the rat COX-2 promoter region (-2698 to +32) and a rat TTF-1 expression plasmid (TTF-1-pcDNA) in C6 glioma and B35 neuroblastoma cells. Here, TTF1 is linked to glioma.