Targeted activation of gene expression dCas9-SAM A gene activation system that consists of a dCas9-VP64 fusion protein, MS2–p65–HSF1 fusion of activational domains, and a modified sgRNA scaffold to recruit the activational domains to the target gene transcription starting site. By recruiting multiple activation factors, the synergistic activation mediator (SAM) system achieves robust transcriptional activation, exceeding the activation levels of dCas9-VP64 alone.