Flow cytometric analysis of normal bone marrow and AML primary cultures exposed to solvent control or to low (10 μmol/L), intermediate (50 μmol/L), and high (100 μmol/L) concentrations of lovastatin for 2 days. Representative primary cultures from each of the three lovastatin response groups are shown, including a nonresponsive sample A, an intermediate responsive sample I, and sensitive samples K, L, and O. The percentage of cells in the pre-G1 (apoptotic) fraction of the cell cycle is shown in the upper left corner of the individual histograms.