Table 1

Average IC50s (± SD) for thioguanine, mercaptopurine, methylmercaptopurine riboside, and methotrexate in CEM-MOCK and CEM-TPMT+ cells after 48 h of incubaton

Inhibition of proliferation was determined using the CellTiter 96 AQueous Assay (Promega) with colorimetric detection of formazan formed at 490 nm. Results summarize three to five experiments at different passage numbers, with four replicates each.
IC50 (μM)P
CompoundMOCKTPMT+
Thioguanine0.55 ± 0.191.10 ± 0.120.02
Mercaptopurine1.50 ± 0.230.52 ± 0.20<0.01
Methylmercaptopurine riboside0.072 ± 0.0460.054 ± 0.0290.38
Methotrexate0.012 ± 0.0050.012 ± 0.0060.27