Figure 2.

Functional analysis of rhodamine 123 accumulation in HeLa cells transiently expressing wild-type ABCG2 and all 19 ABCG2 mutants. Cells were incubated with 0.5 μg/mL rhodamine 123 for 30 min at 37°C. After incubation, cells were harvested by centrifugation and resuspended and incubated in drug-free medium for an additional 30 min at 37°C, followed by analysis of fluorescence by flow cytometry. The percent of accumulation was calculated by dividing the mean fluorescence values obtained for all the variants by the fluorescence value of the pTM1 vector and multiplying by 100.