A breakthrough in genome engineering! The CRISPR/Cas9 (CRISPR-associated protein 9 nuclease) system uses a RNA-guided endonuclease technology which allows for inducing indel mutations, specific sequence replacements or insertions and large deletions or genomic rearrangements at any desired location in the genome. In addition, Cas9 can also be used to mediate up- or downregulation of specific endogenous genes or to alter histone modifications or DNA methylation.