We highly recommend to perform a titration for G418 in a range of 0,1 mg/ml to 1,5 mg/ml; in serum-free culture expand range down to 20 µg/ml).

Choose the concentration which is 0,1 or 0,2 mg/ml above the one which shows complete cell death as the appropriate G418 concentration for selection. If the lowest concentration used shows complete cell death at day 7, the titration should be repeated with a lower concentration range.