Genomic DNA extraction and Junction PCR
Genomic DNAs were purified from pellets of KI cell pools using GeneJET Genomic DNA Purification Kit (Thermo Fisher Scientific) and served as templates for PCR using the Phusion High-Fidelity PCR Master Mix (Thermo Fisher Scientific). To verify TI, 5’ Junction PCR was conducted by touchdown PCR (98°C for 30 s; 10×: 98°C for 10 s, 72–62°C [−1°C/cycle] for 30 s, 72°C for 45 s [short variant of CMV, EF-1α], 1 min [CHEF-1α]; 30×: 98°C for 10 s, 62°C for 30 s, 72°C for 45 s [short variant of CMV, EF-1α], 1 min [CHEF-1α]; 72°C for 10 min). For the generation of double KI monitoring CHO-K1 cell line, out-out and 5’/3’ Junction PCR was performed by touchdown PCR (98°C for 30 s; 10×: 98°C for 10 s, 70–60°C [−1°C/cycle] for 30 s, 72°C for 2 min 10 s [out-out], 1 min 20 s [5’ Junction], 1 min [3’ Junction]; 30×: 98°C for 10 s, 60°C for 30 s, 72°C for 2 min 10 s [out-out], 1 min 20 s [5’ Junction], 1 min [3’ Junction]; 72°C for 10 min). PCR primers are listed in Supplementary Table S3.