Figure 3.

Uridine dose-dependently prevents AICAr-mediated S-phase arrest and the increase in the expression of differentiation markers. U937 cells were incubated with AICAr (0.5 mm), nucleosides (1×), and uridine (30 and 300 μm) for 72 h. A, representative histograms of propidium-labeled cells analyzed by flow cytometry. B, percentage of cells in G₀/G₁, S, and G₂/M phases of the cell cycle. C, the number of viable cells and the expression of differentiation markers were determined as described under “Experimental procedures.” Results are mean ± S.E. (error bars) of at least three independent experiments. *, p < 0.05 compared with control (ctrl).