Induction of cell death <i>in vitro</i> of the indicated xenograft cells.

<p>ALL cells recovered from the spleens of untreated mice were cultured with the indicated concentrations of FTY720 for 16 hours and viability assessed by flow cytometry using annexin V and propidium iodide staining. The viability of cells in control cultures was 42% for xenograft 1345, 90% for xenograft 1999, 93% for xenograft 0398, 51% for xenograft ALL-3, 63% for xenograft ALL-55 and 34% for ALL-56.