G418 accumulation in cells.

(A) G418 was added with or without mefloquine at t = 0 and its total intracellular levels were measured at the indicated times. The solid line shows logarithmic curve fit. (B) Cells were exposed or not to G418 and mefloquine for 24 h and subjected to crude subcellular fractionation to determine cytosolic and organellar G418 concentrations, as well as total cellular G418 concentration. Western analysis shows the amount of TPP1, a lysosomal protein, and GAPDH, a cytosolic protein, in each fraction. Data are expressed as the mean ± SD (n = 3 biological replicates).