design: cell line=HEK293T; FUS N-terminus CCPGCC tag knock-in; without RecT7; sgRNA(FUS)=TGAGCACAGACAGGATCGCA; Primer extension-mediated sequencing (PEM-seq); ReAsH staining and FACS; ~20 ug genomic DNA sonication and primer extension with biotinylated primers; Dynabeads streptavidin enrichment; bridge adapter ligation; nested PCR; gel size selection;