Two human genomic DNAs were chosen as templates to amplify the OPRK1 upstream regions, one containing the indel (6006) and one lacking it (5003). The primer pairs are listed in Table 3; we added a SalI site at the 5′ end and a KpnI site at the 3′ end of the fragments to facilitate cloning into the luciferase reporter plasmid pXP2 (30). Amplified fragments were purified, digested with SalI and KpnI and cloned into pXP2 that was similarly digested. Identity of the fragments was confirmed by restriction mapping and DNA sequencing.
