Western blot was performed on protein extracts from HEK293 cells transfected with a myc-tagged Cas9 using the CRISPR/Cas9 antibody as well as two commercially available purified monoclonal myc tag antibodies (supplier A and B). The three antibodies were used at different dilutions (antibody stocks: purified monoclonal Myc A 1ug/ul, Myc B 1ug/ul and Cas9 1.9ug/ul). The ladder has been revealed by using the HRP coupled Blue ladder antibody. Exposure time was 1 hour.