Promoter activity is unaffected by polymorphic sites. Two promoter variants, I (top) and II (bottom), that included the 2 polymorphic sites previously associated with the P₁/P₂ phenotypes^32-34  were constructed as deletion mutants (the names of which are indicated on the left) and investigated. Polymorphisms are designated as follows: A = −907_−903del, B = −551_−550insC, C = −164A>G, D = −160C>T, and E = −17_+8del. Ramos cells were transfected with construct DNA and Renilla DNA. pGL3-vector with SV40 promoter sequence was used as positive control (gray) for which the luciferase activity was set to 1. pGL3-basic was used as negative control (gray). Values from the different constructs were compared with the SV40 promoter vector value. Luciferase values are shown as white (promoter variant I) or black bars (promoter variant II). The results represent the mean of 3 independent experiments and error bars represent standard error of the mean values. The apparent repressor site located between positions −316 and −240 upstream of the transcription start site was evident in both variants analyzed and has also been reported by Okuda et al.³⁵