NOS2 and colorectal adenocarcinoma: Toell et al. reported that the presence of two GGTTCA motifs is directly repeated and is separated by a distance of four nucleotides (DR4) in the promoter region of the inducible nitric oxide synthase (iNOS) gene in the DLD-1 human epithelioid-like colorectal adenocarcinoma cells to form the response element (RE) of PXR [217].