Fig. 4. The expression of CAT is inhibited when DRE-hrk is located at the 3′ end of the reporter cDNA. The reporter plasmid pTK-CAT containing the DREAM binding sequence of the hrk gene (DRE-hrk), or a random, nonsense sequence of the same size and nucleotide composition (DRE-NS), or the DRE sequence of the prodynorphin gene (DRE-PD), was introduced into HEK 293 cells. After 24 h of transfection, CAT activity was determined relative to that of the pTK-CAT reporter plasmid. Data (mean ± SD) were collected from three independent transfections.