Cell cycle analysis of AML1+/– and +/+ BM cells. (A) Lineage-negative BM cells were labeled with PI and subjected to FACS analysis. Shown are representative PI FACS profiles of wild-type and AML1+/– cells. (B) Total BM cells (TBM) and lineage-negative BM cells (Lin–) were dual-stained with the RNA dye PY and DNA dye Hoechst 33342, and the percentage of G0 cells (PY low, Hoechst low) was determined by FACS. The values shown represent the mean and standard deviation of 6 independent experiments.