The effect of lovastatin on leukemic cell viability determined by trypan blue exclusion. Five hundred thousand cells from two ALL cell lines KK and G2 (A) and two AML cell lines AML-2 and AML-5 (B) were seeded in triplicate and exposed to solvent control or 1, 10, or 20 μmol/L lovastatin for 4 days. The number of viable cells that can exclude the dye trypan blue and the percentage of nonviable cells that stained blue were evaluated daily by microscopy using a hemocytometer. Results shown are the average of the triplicate counts at each timepoint, where the error bars represent the standard deviation of the mean. This experiment was repeated with similar results.