Transfected HEK293 cells overexpressing the N-terminal 1-608 amino acids of S. pyogenes Cas9 . The cells were stained with Anti-Cas9 from Streptococcus Pyogenes Antibody (red) and Anti-Cas9 from Streptococcus Pyogenes Antibody (A85326 | green) giving these cells a yellow appearance. The N-terminal construct contains a nuclear localization sequence and so is predominantly nuclear in localization. Most HEK293 cells in this field are not transfected so only the nuclei of these cells can be visualized with the blue DAPI DNA stain.