Enhanced sensitivity to G418 of human KB cells adapted to certain media and sera

Sensitivity to the neomycin derivative G418 was determined for a human cell line, KB 3-1, that had been adapted to six different combinations of media and sera. The results indicate that while the plating efficiency is similar for all conditions, the susceptibility to G418 can differ markedly depending on the particular combination of media and sera used. This suggests that in experiments using neomycin resistance as a selectable marker, conditions may be found where the amount of G418 required for selection and maintenance of transfected cell lines can be reduced, providing a significant savings.