Immunoprecipitation (IP) of Cas9 and Cas9-nickase by using mouse monoclonal anti-CAS9 antibodies TA811194 and TA811327. Mouse IgG control serves as the negative control. 293T cells were transfected with flag-tagged Cas9 overexpression plasmid, pCas-Guide (G) and pCas-Guide-nickase (N). Overexpression cell lysates were first precleared with ProteinG beads then incubated with beads crosslinked with anti-CAS9 antibody for overnight. The beads were then rinced with buffer and went thro ugh Western Blot analysis using anti-flag antibody (TA180144) (1:30).