Cas9, or “CRISPR associated protein 9,” is a Streptococcus pyogenes-derived nuclease used in the CRISPR/Cas9 genome editing. The technique enables for mutating, inserting or deleting specific regions within the genome. The editing function of Cas9 is mediated by a guide RNA that complements both Cas9 and the targeted DNA sequence. Cas9 may be delivered into cells as a plasmid, as an active protein, as mRNA, or within a viral vector.