Down-regulation of SV40 promoter activity by hDAT intronic 121-bp fragment. a Cloning of the 120-bp fragment into two different locations (indicated by two arrows) in pGL3-Promoter Vector (Vector), resulting in pGL3-SV40+121bp. 121-bp inhibition of SV40 promoter activity, based on Luc activity from Vector versus pGL3-SV40+121bp in two different human cell lines SK-N-AS and BE(2)-M17 (b, c). Arrows indicate two different insertion locations. ANOVA and Tukey tests: *P < 0.05; ***P < 0.001, compared to Vector (N = 4, each in duplicate)