Fig. 6.

Cellular G418 content. A: HPLC assay for detecting G418 derivatized with 1-fluoro-2,4-dinitrobenzene (DNFB). The indicated concentrations of G418 were chromatographed and analyzed as described in materials and methods. Each data point represents the mean value obtained from 3 independent experiments. B: cellular G418 content as a function of extracellular G418 concentration. C: cellular G418 content following the removal of G418 from the extracellular medium. D: immunoblot analysis of NBCe1-A expression following the removal of G418 from the extracellular medium. At time 0, the cells had been exposed to G418 for 24 h.