Note: In order to be able to select for transfected cells by fluorescence-activated cell sorting (FACS), we often use the expression plasmid MSCV-hU6-(BbsI)-CcdB-(BbsI)-PGK-Puro-T2A-BFP carrying a blue fluorescent protein (BFP) reporter (Addgene Plasmid #86457, https://www.addgene.org/86457/; Chu et al. [19]) and transfect into Cas9-expressing suspension cells, such as BJAB lymphoma cells by electroporation. The gene discussed is RNF112; the disease is lymphoma.