PGP and gastric carcinoma: To determine whether or not LysoTracker Red and MitoTracker Red are transport substrates of P‐gp, SW‐1573 human lung carcinoma cells and their doxorubicin‐resistant P‐gp‐expressing subline SW‐1573/2R160 35, as well as EPG85‐257P human gastric carcinoma cells and their daunorubicin‐resistant P‐gp‐overexpressing subline EPG85‐257‐RDB 36 were used.