The CRISPR activation (CRISPRa) system is a variation of the canonical CRISPR-Cas9 used for creation of double-strand breaks in genomic DNA. It utilizes a nuclease-deactivated S. pyogenes Cas9 (dCas9), often called "dead Cas9", that is fused to one or more transcriptional activators. When paired with a well-designed guide RNA that targets a gene near a promoter region, the gene's native transcription start site is activated. Edit-R dCas9-VPR mRNA expresses a human codon-optimized version of the nuclease-deactivated S. pyogenes Cas9 gene, the three transcriptional activators (VP64, p65 and Rta), and two nuclear localization signals (NLS).