Figure 6

Accumulation and retention of free Ara-C (a) and phosphorylated Ara-C (Ara-CxP) (b) in the HEK, HEK/MRP4 and HEK/MRP5i cell lines. T = 4: 4 hours exposure to 10 μM Ara-C, T = 4 + 2: 4 hours exposure to Ara-C followed by 2 hours drug-free medium. Values represent DPM ± SEM of 3 separate experiments. For both free Ara-C and Ara-CxP the effect of drug-free medium was significant (*, p < 0.01) (paired t test). For free Ara-C the accumulation was significantly lower in HEK/MRP4 and HEK/MRP5i cells compared to wild-type HEK cells (+, p < 0.05) (unpaired t-test), for the Ara-CxP this only holds for HEK/MRP4 cells. Accumulation was measured in the absence of indomethacin or probenecid.