The effect of lovastatin on primary cell cultures. (A and B) MTT enzyme activity after exposure to 0 to 150 μmol/L lovastatin for 2 days in bone marrow and cord blood samples as well as a representative sampling of the 22 AML primary cultures analyzed (see Table 1), respectively. The results are the average of six replicates of a single experiment, where the error bars represent the standard deviation of the mean. The MTT activity values were normalized to the solvent controls for each sample and set at 100 for clarity of presentation. (C) Colony growth potential of bone marrow progenitor cells after exposure to 0 to 150 μmol/L lovastatin for 2 days in vitro (BM 4 and BM 5a) or added to the methylcellulose at time of plating (BM 5b) and incubation for 14 days; colonies were scored where the values represent the mean of duplicate readings and error bars as the standard deviation of the mean. (D) Colony growth potential of various AML primary cultures after exposure to 0 to 150 μmol/L lovastatin for 2 days; cells were then plated in methylcellulose and incubated for 7 days. Blast colonies of greater than 50 cells were scored and the values represent the mean of triplicate readings, where the error bars are the standard deviation of the mean.