Table 1

OGAT activity and chemosensitivity to TZM of leukemic cell clones

OGAT activityTZM IC50p
fmol/mg of protein μm
K562 OGAT−5  ± 215  ± 3
K562 OGAT+50  ± 569  ± 5<0.01
U937 OGAT−9  ± 210  ± 2
U937 OGAT+277  ± 4100  ± 3<0.01

Values represent the mean ± standard error of three independent determinations. Cells were exposed to graded concentrations of TZM as described in Materials and Methods. After 72 hr, cells were counted, and IC50 values were calculated on the regression line where the number of cells was plotted versus the log of drug concentration. Probability values were calculated on the basis of Student’s t test analyses.