Figure 1From: No direct effect of the -521 C/T polymorphism in the human dopamine D4 receptor gene promoter on transcriptional activityExpression analysis of the DRD4 gene by RT-PCR. β-actin mRNA levels within the same extracts were used as an internal control. Note that the primers for the DRD4 gene were designed to span the exon 2 and exon 3 boundaries, to control for possible genomic DNA contamination.Back to article page