CRISPR-Cas9 must translocate to the nuclei of the transfected cells for executing its nuclease activity on the genomic DNA. Cas9 protein must be checked through ICC/IF or IHC staining of the transfected cells with CRISPR-Cas9 antibodies.

Check the CRISPR-Cas9 expression levels

The level of the duration of expression of Cas9 protein is very critical when using CRISPR-Cas9 genome editing technology. In stable clones, it is suggested to isolate multiple clones and to screen them for Cas9 expression levels through western blot analysis. In Transient systems, check that Cas9 expression was transient by using western blot and anti-Cas9 antibodies.