Targeted activation of gene expression dCas9-VPR A gene activation system that consists of a dCas9 fused to three transcriptional activation domains: VP64, p65, and Rta (VPR). By targeting dCas9-VPR near the transcription starting site of the target gene using a guide RNA, the transcriptional activation of the target gene can be achieved. The VPR system achieves higher levels of gene activation compared to dCas9-VP64. The advantage of the dCas9-VPR system is that it consists of a single fusion protein, which simplifies the experimental design, compared to the dCas9-SAM and dCas9-SunTag systems.