Figure 1. Modulating miRNA Function. A miR-21 binding site was inserted into the multiple cloning site of the PsiCHECK™-2 vector, at the 3′ end of the Renilla luciferase gene. Upon transfection into HeLa cells, miR-21 binds to its binding site within the PsiCHECK-miR-21 plasmid, causing degradation of the Renilla luciferase gene and, thereby, preventing luminescence. Subsequent transfection with anti-miRNA oligonucleotides (AMOs) targeted to miR-21 leads to AMO binding of miR-21, allowing translation of the Renilla luciferase gene and observed luminescence.