Transport and accumulation of vitamin C in HL60 and U266 cells. HL60 (A) and U266 (B) cells were incubated for the time indicated with 250 μM dehydroascorbic acid (DHA; ○) or ascorbic acid (AA; •) at room temperature. Intracellular accumulation of vitamin C in HL60 and U266 cells treated with DHA for 60 minutes at 37°C (A-B insets). (C) Inhibition of DHA transport in U266 cells treated with cytochalasin E (Cyt E; ○) and B (•). (A-C) Data are expressed as the mean ± SD of 3 independent experiments. iAA indicates intracellular AA.