TABLE 2

IC₅₀ and K_i values for BR and TR inhibition of [³H]uridine transport in yeast producing human nucleoside transporters Rates of transport of 1 μM [³H]uridine into yeast expressing pYPhENT1, pYPhENT2, pYPhCNT1, or pYphCNT3 were measured over 20 or 10 min in the presence of graded concentrations of BR and TR as described in Fig. 3. Mean IC₅₀ ± S.E. values were determined using GraphPad Prism software version 3.0 and then converted to K_i values by the Cheng and Prusoff (1973) equation using K_m values for uridine (Visser et al., 2002, 2004; Zhang et al., 2003).