Kinetin riboside kills primary leukemia cells. The effect of treatment with (A) KR, (B) cytarabine, (C) mitoxantrone, or (D) PTL on bulk leukemia cells from 51 primary AML (black) and 12 CML (gray) samples. (E) KR was more effective against CML than AML. (F) KR was effective against all AML FAB subtypes tested; some samples were unclassified. (G) The IC50 (μM) for each sample for KR, cytarabine, mitoxantrone, and PTL. Gray bar: mean IC50. Open squares indicate CML; closed circles indicate AML (*P < .05, **P < .01, and ***P < .001).