In vitro and in vivo activity of 4-thio-uridylate against JY cells, a model for human acute lymphoid leukemia

► s4UMP a naturally occurring thiolated nucleotide, effectively inhibited the proliferation of JY cells in vitro and in vivo. ► s4UMP decreased the cell number and colony forming activity of leukemia cells in SCID mice. ► The effect of s4UMP was undetectable on the bone marrow of healthy mice. ► The biochemical changes of the treated cells suggested that s4UMP induced apoptosis.