Fgh1tutg lentivirus vector

To express dCas9-KRAB protein, lentivirus was made using pLV hU6-sgRNA hUbC-dCas9-KRAB-T2a-Puro lentivirus vector (500 ng; Addgene plasmid #71236) together with packaging plasmids pMDLg/pRRE (250 ng), pRSV-Rev (250 ng) and the envelope plasmid pMD2.G (250 ng). Kelly cells were infected with virus medium using the same method mentioned in previous section. The cells were selected by puromycin (0.5 μg/mL) for 3 days. Subsequently, dCas9-KRAB expressing cells were transduced with an inducible sgRNA and a GFP gene. The sgRNA sequences were designed and cloned into FgH1tUTG lentivirus vector (Addgene#70183) at the BmsBI digestion site. Lentivirus were made using the vector by the method mentioned above. After 4 days of transduction of the sgRNA vector, the cells were selected by GFP signal by flow cytometry using the BD FACSAria II (BD Biosciences). The cells were then treated with 1000 ng/mL DOX to induce a sgRNA expression. The sgRNA sequences were designed using CRISPR Design Tool (http://crispr.mit.edu/) and shown in Supplementary Data 5.