HEK293 cells expressing EGFP-hAQP9 are more sensitive to arsenite than HEK293 cells expressing YFP-hDAT.

A-C) Native HEK293 cells and HEK293 cells expressing EGFP-hAQP9 or YFP-hDAT were grown in 96-well plates and exposed to different concentrations of arsenite (eight wells for each concentration). Cell viability was assessed after 24 hours using the MTT assay. Data were collected from independent plates (n = 3 for each construct) and normalized to respective untreated cells. Both EGFP-hAQP9 and YFP-hDAT expressing cells showed higher sensitivity to arsenite, than native HEK293 cells, with EGFP-hAQP9 cells being the most sensitive. At the arsenite concentration of 10 μM, stably transfected EGFP-hAQP9 were the only cells showing toxin sensitivity (A). The curve showing IC50 values for arsenite calculated by nonlinear regression, log(inhibitor) vs response (three parameters) is shown (B). For log transformed data, the concentration 0 was set to 1 nM. Comparison of the IC50 values shows a significantly lower IC50 value for the HEK293 cells expressing EGFP-hAQP9 compared to the native HEK293 cells or HEK293 cells expressing YFP-hDAT (C). Bars are mean ± SEM. Asterisks: significantly different from untreated controls; *p<0.05, **p<0.01, ***p<0.001; crosses: significantly different from previous data point: ++ p<0.01.