Comparative cytotoxic effect of tachpyr and desferioxamine on cultured MBT2 bladder cancer cells. Cells were incubated with varying doses of desferioxamine mesylate or tachpyr for 72 hours and viability was assessed by using an MTT assay as described in the Materials and Methods. Calculated IC₅₀s from this data are 3.6 μmol/L for tachpyr and 70 μmol/L for desferioxamine. Mean IC₅₀ of tachpyr in four independent experiments was 4.6 ± 2.0 μmol/L (standard error).