Fig. 3.

Substrate and concentration dependence of transport. Influx of [³H]MTX, [³H]pemetrexed, [³H]5-formyltetrahydrofolate (5-formylTHF), [³H]5-methyltetrahydrofolate (5-methylTHF) and [³H]folic acid was assessed at substrate concentrations of 1 and 100 μM at pH 5.5 over 1 min at 37°C. Data are the means ± SE from 3 experiments performed on different days.