Selection of transfected CHO cells using G418

Transfected cells were cultured with DMEM/F-12 supplemented with 10% FBS at 37°C, 5% CO₂ atmosphere, for 2 d. Two mg/mL of the aminoglycoside antibiotic G418 (a selection agent) was added to culture medium for 2 d, and cells were washed with PBS solution 3 times. Remaining adherent cells were cultured with DMEM/F-12 with 10% FBS for 1 d, collected, and positive cell percentage was measured by flow cytometry.